Editing Rearend identification


==Introduction==
There are several ways to tell what the type/size/application of a rearend. Besides visually checking and comparing rearends to one another, there are casting numbers, build codes and dates displayed or cast/stamped in various locations on the rearend and elsewhere. These all can be used to help ID a rearend.

==Casting numbers==
Many if not all rear end housings will have some sort of casting number or ID cues to identify it. If the RPO decal is present (newer vehicles) or the broadcast or "build" sheet is available, it can show what was originally in the vehicle. Sometimes body/fender/cowl tags contain coded info that may list specifics on the rearend.


==Axle codes==
[[File:Rearaxlecode1.jpg|thumb|left|400px|Example of GM stamped axle code]]GM axles are stamped on the axle tube (and sometimes the center section) with codes for the year and ratio. Sometimes the casting numbers can also be used to show whether an axle housing is a limited slip differential (LSD) or not.
<br style="clear:both"/>

Some sites with ratio and axle code info are:
*[http://www.novaresource.org/axle.htm Axle Codes] from novaresource.org
*[http://www.thecamaro.com/Decoding/Chevy-Axle-Rear-End-Decoding/ Chevrolet Rear Axle Code Identification and Decoding] from thecamaro.com 
*[http://www.thecamaro.com/Decoding/Chevy-Axle-Rear-End-Decoding/Chevy-Full-Size-Rear-Axle-Codes.php Chevrolet Full Size and Impala Rear End/Axle Assembly Codes] from from thecamaro.com
*[http://tech.oldsgmail.com/axle_useage.php GM A-body codes] from tech.oldsgmail.com
*[http://www.gnttype.org/numbers/axcodes.html Gear ratio info] from gnttype.org
*[http://www.v8monza.com/Rearaxle.htm H-body axle codes] from v8monza.com

Ford rear ends sometimes had tags under one of the carrier bolts that had the ratio and a code for being a LSD or not. Ford also used an axle code on the body tag on some models.

==Date codes==
The date code format can vary, but sometimes the date code is a letter followed by two or three numbers. The letter is the month. The next number or two numbers will be the day of the month. The last number is the last digit of the year. 
:Example: '''C124''' 
:*C = March (A = Jan., B = Feb., etc.)
:*12 = day of the month
:*4 = year ending in 4, i.e. 1964, 1974, 1984, etc.

==Axle dimensions==

===Axle flange dimensions===
[[File:Rear end axle flange id.jpg|thumb|left|600px|Axle flange dimensions from [http://moparinterests.blogspot.com/2010/09/mopar-rear-axle-dimensions.html Moparinterests blogspot.com]]] <br style="clear:both"/>

===GM removable carrier type===
The removable carrier rear end was used by GM for a number of years in passenger cars before GM started using the integral carrier rear end. The Pontiac/Olds versions from the later '50s were a drag racing mainstay for many years- even in front engined Top Fuel dragsters and Altereds.

===1955-'64 carrier casting numbers===
3 series (2.73:1- up): '''410408N'''
 
2 series (2.56:1- down):'''410409N'''
The Chevy version used various tags to designate the ratio.

[[File:GM DIFF ID TAGS.jpg]] <br style="clear:both"/> 

===Casting numbers and casting codes===
*The casting number for a 1956 case should be 3707306
*The casting number for a 1957-'61 non-posi center case should be 3725899
*The casting number for a 1957-'61 posi center case is 3743833
*The casting number for a 1962-'64 posi center case is 3789812

The above are all casting numbers for passenger cars. These casting numbers are the same for Corvette rearends because the rearends were cast and assembled at just two facilities: the Detroit Gear and Axle plant and the Buffalo, NY plant. The only thing that would be different between the same year Corvette and a passenger car rearend center section would be the stamped (not cast) two letter code on the passenger side of the case. The code designates the gear ratio.

==Ford==
*[http://www.fordification.com/tech/rearends_ford01.htm Ford Rear Axle Assembly Identification] Stamped axle codes
Ford used a vast array of rear ends over the years. Besides the codes stamped into the axle tubes, some carried ratio and/or posi tags as well as the vehicle having a plate containing coded info on the rearend. Below are photos of some of the more common rear ends for visual reference and comparison:

==Removable carrier==
[[Image:9inch.jpg|thumb|left|400px|Removable carrier, rear view.]] <br style="clear:both"/>

====ID====
An easy way to tell the difference between the 8-inch and the 9-inch Ford differential is that on an 8-inch, a socket will fit on the lower nuts seen in this picture. Since the pinion centerline is lower on a 9-inch, a wrench is needed to gain clearance.

===8 inch===
{|
|[[File:8inford.jpg|thumb|600px|center|8 inch Ford front view]]
|[[File:9inchrear1.jpg|thumb|center|400px|8 inch Ford differential details. Note the accessibility of the bottom bolts indicating it's not a 9 inch.]]
|}

===9 inch===
One of the strongest Ford rear end was the 9". Still one of the best rearends to modify or use in stock form to handle big horsepower.

[[Image:DSC02404.JPG|thumb|left|500px|9 inch Ford rearend]] <br style="clear:both"/>

===9-3/8 inch===
Removable carrier. Found in some Lincoln, Mercury and Thunderbird.

==Non-removable carrier (Salisbury-style rearend)==
===8.8 inch===
{|
|[[File:8.8 truck.jpg|thumb|center|400px|8.8" rear end in a Ford F150 4X4]] 
|[[File:Ford 8.8 w damper weight.jpg|thumb|center|180px|8.8" rear end with damper weight attached]]
|}

===8.7 inch===
Non-removable carrier. Found in Granada, Monarch 1977 to 1978. 

[[Image:87rear.jpg|thumb|left|500px|8.7 inch Ford rear end]] <br style="clear:both"/> 

===7.75 inch===
Non-removable carrier. Found in Fairlane.

===7.5 inch===
Non-removable carrier. Found in light duty applications such as six cylinder Falcon, Fairlane and 170 cid Maverick (Mavericks powered by 200 cid, 250 cid and 302 cid engines had the 8-inch differential).  

===7.25 inch===
Non-removable carrier. Found in Falcon, Econoline, Fairlane, Comet.

===7 inch===
Non-removable carrier. Found in Falcon.

===6.75 inch===
Non-removable carrier. Found in some Pinto and Mustang II.

[[File:Pintorear.jpg|border|450px]]

===Columbia 2-speed rear end===
More of an overdrive unit than an actual rear end. Included in the Ford section since it was offered as an option on '30s to '40s Fords.

==General Motors==
==GM diff covers==
[[File:Gm axle covers.jpg|left|frame|GM diff covers]]
<br style="clear:both"/>

[[File:GM 10bolt id.jpg]]

[[Image:10bolt.jpg|thumb|left|500px|10 bolt 8.5 inch GM corporate rear end]]
<br style="clear:both"/> 

*[http://chevellestuff.net/qd/index.htm Axle codes by year]
 
===10 bolt===
=====10 bolt ID tips=====
If you don't have the codes on hand to identify if a 10 bolt rear end is an 8.5" or not, you can measure the distance between the very bottom bolt for the cover and the next adjacent bolt (either right of left), it will be 3-3/4" for a 8.5" and 3-1/4" for a 7.5".<br>
{{Note1}}Some installation kits for the 8.5" and 7.5" use ring gear bolts with a 5/8" head, so if someone has rebuilt the rearend with one of these kits the bolts will have smaller heads than the original bolts.

Another [http://www.hotrodders.com/forum/need-id-gm-10-bolt-163067.html#post1571160 tip] is to check the size of the pinion nut. The 8.2" uses a 1-1/8 inch socket on the nut and the 7.5" and 8.5" use a 1-1/4 inch socket. That is as long as they have a OEM type nut on them.

There are usually two distinctive lugs cast into the bottom of the 10 bolt rear end housing. These lugs are arrowed in the image above. 

The ring gear of the corporate 10 bolt is secured by 7/16-20 '''left hand''' thread bolts having a 3/4" hex head on them; there will be ten bolts holding the ring gear to the differential. The ring gear is (as mentioned) 8.5" diameter and the pinion shaft diameter is the same as the 12 bolt at 1.625". The 8.5" pinion has 30 splines.

The 8.2" diff will have 10 bolts holding the ring gear on the diff, the bolts will have a 9/16" hex head and be right hand threaded. The 8.2" uses ten 3/8-24 right hand thread bolts to hold the ring gear on the diff. The pinion diameter is 1.438", having 25 splines.

The 7.5" diff will have the ring gear secured with 10 bolts that are 7/16-20 LH thread, like the 8.5" corporate rear end. However, the ring gear diameter is smaller than the 8.5" differential.

====8.75 inch 10-bolt====
This rearend was used in some mid-'70s Chevrolet station wagons, Impala, Caprice, some Chevelles, El Caminos, usually with larger engines and/or heavy duty options (towing, etc.). Also ''possibly'' found in some Pontiac LeMans, some 1977 Buick Regals and Cadillac models (needs confirmation).

Can be found with either 28 or 31 spline axles. It has a 10-bolt cover with indentions next to the axle tubes and 12 bolts holding the ring gear to the carrier (the bolts have a 3/4" hex head, right hand threads). The pinion nut is 1-1/4", it has 3" axle tubes.

This is a strong rearend, but unfortunately it was only used briefly and aftermarket support is poor.

[[File:8 3-4 gm diff.jpg|thumb|left|GM 8.75" 10-bolt rear cover]]<br style="clear:both"/>

====8.5 inch 10-bolt====
Sometimes referred to as the "corporate 10-bolt", the GM 8.5" 10-bolt rearend began production in 1971 to replace the 8.2" and 12-bolt rearends. There was simultaneous use of the 8.2" and 8.5" rearends during the changeover period, like in the Nova. Has a 10 bolt cover as well as 10 bolts securing the ring gear. Ring gear bolts are 7/16 - 20 LH threads (also shared with the 7.5/7.625"). 

The 8.5" 10-bolt GM rearend has a 30 spline pinion, uses C-clips, and could have 28 or 30 spline axles depending on the year (30 spline axles were used after 1988). 4 wheel drive 8.5" front differentials manufactured between 1977-91 share the same differential gears, bearings, and pinion seals but has a modified housing and cover which has an indentation to clear suspension travel. It uses a 1-1/4" pinion nut. Ring gear diameter was increased to 8.6" when used with the GMT800 platform light duty trucks (1999-06 Silverado/Sierra). 
<table  bgcolor="#F9F9F9" table border="1" cellpadding="2" cellspacing="0"><tr>			<td>                                 Apollo:&nbsp;&nbsp;1973 - 1975&nbsp;&nbsp;
                                </td><td>                                    Bel Air:&nbsp;&nbsp;1970 - 1975&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                   Blazer:&nbsp;&nbsp;1979 - 1994&nbsp;&nbsp;
                                </td><td>                                    Bonneville:&nbsp;&nbsp;1970 - 1986&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    C10 1/2 Ton (2WD):&nbsp;&nbsp;1979 - 1987&nbsp;&nbsp;
                                </td><td>                                    C15/ C1500 1/2 Ton (2WD):&nbsp;&nbsp;1979 - present&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    C1500 1/2 Ton (2WD):&nbsp;&nbsp;1988 - 1998 (incl. GMT400-based Blazer (92-94), Tahoe/Yukon, Escalade, Denali, 1/2 ton Suburban)&nbsp;&nbsp;
                                </td><td>                                    Camaro:&nbsp;&nbsp;1970 - 1981&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Caprice:&nbsp;&nbsp;1970 - 1996 (includes '94-'96 Impala SS and 9C1 police package)&nbsp;&nbsp;
                                </td><td>                                    Catalina:&nbsp;&nbsp;1970 - 1981&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Chevelle/Malibu:&nbsp;&nbsp;1973 - 1973&nbsp;&nbsp;
                                </td><td>                                    Cutlass:&nbsp;&nbsp;1970 - 1977&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Cutlass:&nbsp;&nbsp;1985 - 1987 (442 package)&nbsp;&nbsp;
                                </td><td>                                    El Camino:&nbsp;&nbsp;1971 - 1976&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Electra:&nbsp;&nbsp;1971 - 1989&nbsp;&nbsp;
                                </td><td>                                    Firebird:&nbsp;&nbsp;1970 - 1981&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    G10 1/2 Ton:&nbsp;&nbsp;1979 - 1989&nbsp;&nbsp;
                                </td><td>                                    G15/ G1500 1/2 Ton:&nbsp;&nbsp;1979 - 1988&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    G20 3/4 Ton:&nbsp;&nbsp;1975 - 1989&nbsp;&nbsp;
                                </td><td>                                    G25/ G2500 3/4 Ton:&nbsp;&nbsp;1978 - 1988&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Grand Prix:&nbsp;&nbsp;1971 - 1987&nbsp;&nbsp;
                                </td><td>                                    GTO:&nbsp;&nbsp;1970 - 1977&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Impala/Caprice:&nbsp;&nbsp;1971 - 1996 ('77-'96 B, C, and D platform for station wagons, diesels, 9C6 (taxicab) and 9C1 police package&nbsp;&nbsp;
                                </td><td>                                    K10/ K1500 1/2 Ton (4WD):&nbsp;&nbsp;1979 - present&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    K15/ K1500 1/2 Ton (4WD):&nbsp;&nbsp;1979 - present&nbsp;&nbsp;
                                </td><td>                                    K5 Blazer (4WD):&nbsp;&nbsp;1979 - 1991 (1979-'82 are overlap years - also applicable to C/K 10 series incl. Suburban&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    LeMans:&nbsp;&nbsp;1971 - 1983&nbsp;&nbsp;
                                </td><td>                                    Malibu:&nbsp;&nbsp;1973 - 1983&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Monte Carlo:&nbsp;&nbsp;1973 - 1978&nbsp;&nbsp;
                                </td><td>                                    Nova:&nbsp;&nbsp;1970 - 1979&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Omega:&nbsp;&nbsp;1973 - 1979&nbsp;&nbsp;
                                </td><td>                                    Phoenix:&nbsp;&nbsp;1978 - 1979&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Regal:&nbsp;&nbsp;1973 - 1987&nbsp;&nbsp;
                                </td><td>                                    Regal:&nbsp;&nbsp;1985 - 1987&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Riviera:&nbsp;&nbsp;1975 - 1978&nbsp;&nbsp;
                                </td><td>                                    Skylark:&nbsp;&nbsp;1970 - 1972&nbsp;&nbsp;
                                </td>
                </tr><tr>
			<td>                                    Skylark:&nbsp;&nbsp;1975 - 1979&nbsp;&nbsp;
                                </td><td>                                    S10,Sonoma:&nbsp;&nbsp;1995 - 2003 (4WD with ZR2 option, S10 SS, Xtreme, and 4.3L trucks with a manual transmission option&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Suburban 1/2 Ton:&nbsp;&nbsp;1979 - 1991&nbsp;&nbsp;
                                </td><td>                                    Suburban 1/2 Ton:&nbsp;&nbsp;1979 - 1991&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Suburban 1/2 Ton:&nbsp;&nbsp;1979 - 1991&nbsp;&nbsp;
                                </td><td>                                    Suburban 1/2 Ton:&nbsp;&nbsp;1979 - 1991&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Trans Am:&nbsp;&nbsp;1970 - 1981&nbsp;&nbsp;
                                </td><td>                                    Ventura:&nbsp;&nbsp;1976 - 1977&nbsp;&nbsp;
                                </td>
		</tr>	</table><br>

====8.2 inch 10-bolt====
The 8.2" rearend was used through 1970 in the B-body (Impala) and F-body (Camaro) cars. The 8.2" was used through 1971 in the X-body (Nova) and through 1972 in the A-body (Chevelle). 
<table bgcolor="#F9F9F9" table border="1" cellpadding="2" cellspacing="0"><tr>
			<td>                                    Bel Air:&nbsp;&nbsp;1964 - 1972&nbsp;&nbsp;
                                </td><td>                                    Biscayne:&nbsp;&nbsp;1964 - 1972&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Camaro:&nbsp;&nbsp;1967 - 1970&nbsp;&nbsp;
                                </td><td>                                    Caprice:&nbsp;&nbsp;1965 - 1971&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Chevelle/ Malibu:&nbsp;&nbsp;1964 - 1972&nbsp;&nbsp;
                                </td><td>                                    Chevy II:&nbsp;&nbsp;1964 - 1968&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    El Camino:&nbsp;&nbsp;1964 - 1972&nbsp;&nbsp;
                                </td><td>                                    Impala:&nbsp;&nbsp;1964 - 1972&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Monte Carlo:&nbsp;&nbsp;1970 - 1972&nbsp;&nbsp;
                                </td><td>                                    Nomad:&nbsp;&nbsp;1968 - 1972&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Nova:&nbsp;&nbsp;1964 - 1972&nbsp;&nbsp;
                                </td><td>                                    Skylark:&nbsp;&nbsp;1964 - 1969&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Tempest:&nbsp;&nbsp;1964 - 1970&nbsp;&nbsp;
                                </td><td>                                    Trans Am:&nbsp;&nbsp;1969 - 1972&nbsp;&nbsp;
                                </td>
		</tr><tr>
			<td>                                    Ventura:&nbsp;&nbsp;1971 - 1971&nbsp;&nbsp;
                                </td><td>                                    Wildcat:&nbsp;&nbsp;1964 - 1972&nbsp;&nbsp;
                                </td>
		</tr>	</table><br>

====10 bolt carriers====
The corporate 10 bolt 8.5 inch rear end uses two different carrier series depending on the rear gear ratio:
*2.56 and higher gears ("higher" gears have lower numbers, like 2.41, 2.29, etc.) go on the 2 series carrier
*2.73 and lower ("lower" gears = higher numbers, like 3.08, 3.23, etc.) go on the 3 series carrier

A 3-series gear can be installed on a 2-series carrier by using a [http://www.summitracing.com/parts/MRG-908A/?rtype=10 ring gear spacer], but this is not advised for stick shift applications, or if there's a lot of traction, HP and/or weight involved.

[[File:Copo 10-bolt ring gear spacer.jpg|thumb|left|450px|Mr. Gasket p/n 908A ring gear spacer for the 8.5" GM 10-bolt 2-series carrier]] <br style="clear:both"/>

==8.5" non C-clip rearend==
The non C-clip differential share the same ring/pinion (incl. pinion bearings, differential carrier) with the C clip version but has pressed on axle bearings similar to a Dana 44 or Ford 9 inch. Differential cover looks similar to the BOP 8.2 10 bolt. 

The 1971-'72 Buick GS/Skylark and Olds Cutlass A-body 8.5 10 bolt did not have C-clip axles. 

The non C-clip 8.5" 10 bolt, type "C" rearend was used in some 1969-'72 Pontiac GP and 1970-'72 Monte Carlo. 

There have been non C-clip rearends found in Chevelle wagons, and some El Caminos through at least 1974.

==12-bolt cover/10-bolt ring gear==
This "O" (Olds) rearend was used in the Olds Cutlass A-body from 1968-'70. It was the rearend that had a 12 bolt cover, but with a 10 bolt 8.5" ring gear. This is '''not''' the same as the corporate 8.5 rearend, and there is no parts interchange between the two rearends.

==12-bolt car==
*Ring gear diameter:  8.875"
*Cover bolts:  12
*Ring gear bolts:  12
*Axle spline count:  30
*Pinion spline count:  30
*Carrier Breaks:  2.76-down / 3.07 / 3.90 / 4.10-up
*Pinion Nut Size:  1-1/8"
Pinion yokes interchange between the 12-bolt car and truck. Originally the 12-bolt rearend used U-joint sizes 1310, 1330 or GM 3R series. 

<table bgcolor="#F9F9F9" table border="1" cellpadding="2" cellspacing="0"
><tr>
			<td>                                    Bel Air:&nbsp;&nbsp;1964 - 1972&nbsp;&nbsp;(Rear)
                                </td><td>                                    Biscayne:&nbsp;&nbsp;1964 - 1972&nbsp;&nbsp;(Rear)
                                </td>
		</tr><tr>
			<td>                                    Camaro:&nbsp;&nbsp;1967 - 1972&nbsp;&nbsp;(Rear)
                                </td><td>                                    Caprice:&nbsp;&nbsp;1966 - 1970&nbsp;&nbsp;(Rear)
                                </td>
		</tr><tr>
			<td>                                    Chevelle/ Malibu:&nbsp;&nbsp;1964 - 1972&nbsp;&nbsp;(Rear)
                                </td><td>                                    Chevy II:&nbsp;&nbsp;1964 - 1968&nbsp;&nbsp;(Rear)
                                </td>
		</tr><tr>
			<td>                                    El Camino:&nbsp;&nbsp;1965 - 1972&nbsp;&nbsp;(Rear)
                                </td><td>                                    GTO:&nbsp;&nbsp;1970 - 1972&nbsp;&nbsp;(Rear)
                                </td>
		</tr><tr>
			<td>                                    Impala:&nbsp;&nbsp;1964 - 1972&nbsp;&nbsp;(Rear)
                                </td><td>                                    Monte Carlo:&nbsp;&nbsp;1970 - 1972&nbsp;&nbsp;(Rear)
                                </td>
		</tr><tr>
			<td>                                    Nomad:&nbsp;&nbsp;1968 - 1972&nbsp;&nbsp;(Rear)
                                </td><td>                                    Nova:&nbsp;&nbsp;1964 - 1972&nbsp;&nbsp;(Rear)
                                </td>
		</tr><tr>
			<td>                                    Trans Am:&nbsp;&nbsp;1969 - 1972&nbsp;&nbsp;(Rear)
                                </td><td>                                    Wildcat:&nbsp;&nbsp;1964 - 1972&nbsp;&nbsp;(Rear)
                                </td>
		</tr>
	</table><br>


==U-joints==
*1310 series, (aka "small Chevy") has 1.063" diameter caps, 3.219" measured across to lock ring points (1-1/16" x 3-7/32"), uses outside clips. Was OEM for many 1967-74 GM cars. Also used with Ford F100s (including early F150s prior to 1980), Broncos, Econolines with 9 inch differentials and AMC/Jeep products (pinion to driveshaft location - driveshaft to transmission yoke used a hybrid U-joint with outside and inside clips)<br> 
{{Note1}}There's also a 1310 "special" U-joint, which has two 1-1/16" and two 1-1/8" caps. Used OE on some Fords and available from the aftermarket as an adapter U-joint.
*1330 series pinion yokes use locating tabs to center the U-joint, has 1.063" diameter caps, 3.625" measured across to lock ring points (1-1/16" x 3-5/8"), uses outside clips. Used on heavy-duty/high performance/big engine applications.
*GM 3R series is the "inside C-clip", or "inside lock" style. Used ~1975-up. It does not use locating tabs. It has 1.125" diameter caps, 2.5625" measured across caps (1-1/8" x 2-9/16"), aftermarket/replacement U-joints uses inside clips, originals use plastic injection.

On the 12-bolt, the hardware used to hold the U-joint into the pinion yoke was either two 5/16" U-bolts, or 4 bolts and 2 metal straps. Both styles were used on original equipment applications. The U-bolts are the preferred method, if for no other reason than if either were to fail the U-bolt type can be easily replaced while the strap type might break off the bolt inside the yoke, making extraction difficult.
[[File:U-jnt girdle.jpg|right|200px]]
The yokes may be different for straps or U-bolts. The strap yoke (if smaller) can be drilled out to use U-bolts, but in some cases this leaves too little metal around the holes. A better approach is to use a yoke made for U-bolts in the first place.

U-joint girdles (right) can be used to replace the original hardware. Be sure to match the diameter of the fasteners to the hole size of the yoke.
*[http://www.actionmachineinc.com/ujointmeasuringguide.aspx U-joint measuring guide]

==MOPAR==
[[File:Dana tags.jpg|left|thumb|350px|Dana diff tags]]
[[File:Dana axle covers.jpg|left|frame|Dana diff covers]]
<br style="clear:both"/>

*[[Mopar rear axle spotter's guide]]
*[[Mopar tapered axle rear brake conversion]]

==AMC==

===ID===
AMC axle codes are stamped on the differential casting between the cover and the tube weld hole on the passenger side) beginning in 1970 for the AMC 20 series rearend, 1972 for the AMC 15 series.
First four letters/ratios are 1970 rear axle codes stamped on the differential housing cover flange at about 3 o'clock:
 
A = 3.54:1
B = 3.15:1
C = 2.87:1
D = 3.91:1
E = 3.58 (12/43)
F = 3.08 (13/40)
G = 3.31 (13/43)
H = 2.73 (15/41)
J = 2.37 (19/45)

The 15 series had 10 bolt oval cover with drain plug center right.

===15 series rearend===
The AMC 15 series rearend has a 7-9/16" ring gear. It was used in 1965 and earlier models with 196 ci or 199 ci inline 6 engines. The small cars (cars other than those listed below as "big car") used the AMC 15 rearend with inline 6 engines, AMC 20 rearend was used with V8 engines. The AMC 20 rearend could be ordered in fleet cars with inline 6 engines. AMC sold the tooling equipment for its differentials to the Dana Corporation in 1985. The AMC 15 was modified by Dana and rebranded as the Dana 35/35C. Ring/pinion sets including the axleshafts do not interchange with the AMC 15.

===20 series rearend===
The big cars (Ambassador, Classic, Rebel, Matador and Marlin) used the AMC 20 rearend with 232 ci inline 6 and bigger engines.

The series 20 was used in Jeeps as well as AMC passenger cars.  A Jeep 20 series rearend would have a 5 on 5" wheel bolt pattern. Passenger cars used the 5 on 4-1/2" wheel bolt pattern.

[[File:Amc 20 series rearend.jpg|thumb|450px|left|20 series under a 1966 Rouge]] <br style="clear:both"/> 
 
==GM RPO axle codes==
<div><font size="1"><table style="float: left;" border="1" cellpadding="2" cellspacing="0"><td>G80</td>
			<td colspan="3" height="13"> Axle  Positraction, Limited Slip</td>
			<td>
			<div align="center">
			</div>
			<br>
			</td>
		
		<tr height="13">
			<td>G81</td>
			<td colspan="3" height="13"> Positraction Rear Axle </td>
			<td>
			<div align="center">
			</div>
			<br>
			</td>
		</tr>
		<tr height="13">
			<td>G82</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			4.56
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>G84</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			4.10
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>G86</td>
			<td colspan="3" height="13"> Axle , Rear, Limited Slip</td>
			<td>
			<div align="center">
			</div>
			<br>
			</td>
		</tr>
		<tr height="13">
			<td>G87</td>
			<td colspan="3" height="13"> Ring Gear, 8.50 Inch</td>
			<td>
			<div align="center">
			</div>
			<br>
			</td>
		</tr>
		<tr height="13">
			<td>G89</td>
			<td colspan="3" height="13"> Ring Gear, 7.50 Inch</td>
			<td>
			<div align="center">
			</div>
			<br>
			</td>
		</tr>
		<tr height="13">
			<td>G90</td>
			<td colspan="3" height="13">Rear</td>
			<td>
			<div align="center">
			3.15
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>G91</td>
			<td colspan="3" height="13"> Special Highway Rear Axle  </td>
			<td>
			<div align="center">
			3.08
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>G94</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.31
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>G96</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.55
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>G97</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.73
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GH0</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.54
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GH2</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.29
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GH3</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.77
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GH4</td>
			<td colspan="3" height="13"> Axle  Rear (2LS V6 Camaro)</td>
			<td>
			<div align="center">
			2.92
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GH7</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			2.73
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GJ1</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			5.38
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GJ2</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			5.13
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GK7</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			4.78
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GK8</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			4.33
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GK9</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			4.63
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GL0</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			5.13
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GL3</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			6.17
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GM1</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.59
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GM2</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			3.44
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GM3</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.45
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GM4</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			3.67
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GM5</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			3.89
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GM6</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			4.22
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GM7</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			3.68
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GM8</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.56
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GN9</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			4.11
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GS1</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.73
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GS3</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.73
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GS4</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.70
			</div>
			</td>
		</tr><tr height="13">
			<td>GS5</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			4.11
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GS6</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			4.56
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GS8</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			3.94
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GT1</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.56
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GT2</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.29
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GT4</td>
			<td colspan="3" height="13"> Axle  Rear (DUP WITH 5 X 1)</td>
			<td>
			<div align="center">
			3.73
			</div>
			</td>
		</tr></table></font> </div>
		<div><font size="1"><table style="float: center;" border="1" cellpadding="2" cellspacing="0">
		<tr height="13">
			<td>GT5</td>
			<td colspan="3" height="13"> Axle  Rear (DUP WITH GT8)</td>
			<td>
			<div align="center">
			4.10
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GT7</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.33
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GT8</td>
			<td colspan="3" height="13"> Axle  Rear (DUP WITH GT5)</td>
			<td> 
			<div align="center">
			4.10 
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GU1</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.41
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GU2</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.73
			</div>
			</td>
		</tr>
<tr height="13">
			<td>GU3</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.93
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GU4</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.08
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GU5</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.23
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GU6</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.42
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GU7</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			2.77
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GU8</td>			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			3.90
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GU9</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			3.91
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GV0</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			3.55
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GV1</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.73
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GV2</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			5.83
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GV3</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.08
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GV4</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.36
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GV5</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.55
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GV7</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			4.11
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GV8</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.72
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GV9</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			4.25
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GW2</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.56
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GW3</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.56
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GW4</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.31
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GW5</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			2.73
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GW6</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.27
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GW8</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			4.10
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GW9</td>
			<td colspan="3" height="13"> Axle  Rear (DUP WITH GU3)</td>
			<td>
			<div align="center">
			2.93
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GX1</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.70
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GX2</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.07
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GX3</td>
			<td colspan="3" height="13"> TransAxle  Final Drive </td>
			<td>
			<div align="center">
			3.33
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GX4</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			3.75
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GX5</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			4.09
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GX6</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			3.53
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GX8</td>
			<td colspan="3" height="13">TransAxle  Final Drive </td>
			<td>
			<div align="center">
			3.74
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GY2</td>
			<td colspan="3" height="13"> Axle  Rear</td>
			<td>
			<div align="center">
			3.31
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GY3</td>
			<td colspan="3" height="26">TransAxle  Final Drive</td>
			<td>
			<p align="center">
			4.29
			</p>
			</td>
		</tr>
		<tr height="13">
			<td>GY4</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			4.53
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GY5</td>
			<td colspan="3" height="13">Axle  Front</td>
			<td>
			<div align="center">
			3.65
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GY7</td>
			<td colspan="3" height="13">TransAxle  Final Drive</td>
			<td>
			<div align="center">
			4.18
			</div>
			</td>
		</tr>
		<tr height="13">
			<td>GY9</td>
			<td colspan="3" height="13">Axle  Rear</td>
			<td>
			<div align="center">
			4.31
			</div></td></tr></table></font><br><br>

==GM ratio to tooth count==
<table border="1" cellpadding="2" cellspacing="0"><tr bgcolor="#dddFFF"><td align="center"><b>Axle Ratio</b></td>
<td align="center" valign="top"><b>Tooth Combination</b></td></tr>
<tr><td align="center">2.56:1</td><td align="center">41/16</td></tr>
<tr bgcolor="#F1F1F1"><td align="center">2.73:1</td><td align="center">41/15</td></tr>
<tr><td align="center">2.92:1</td><td align="center">41/14</td></tr>
<tr><td align="center">3.07:1</td><td align="center">43/14</td></tr>
<tr bgcolor="#F1F1F1"><td align="center">3.08:1</td><td align="center">40/13</td></tr>
<tr><td align="center">3.08:1</td><td align="center">37/12</td></tr>
<tr bgcolor="#F1F1F1"><td align="center">3.31:1</td><td align="center">43/13</td></tr>
<tr><td align="center">3.36:1</td><td align="center">37/11</td></tr>
<tr bgcolor="#F1F1F1"><td align="center">3.42:1</td><td align="center">41/12</td></tr>
<tr><td align="center">3.55:1</td><td align="center">39/11</td></tr>
<tr bgcolor="#F1F1F1"><td align="center">3.73:1</td><td align="center">41/11</td></tr>
<tr><td align="center">4.10:1</td><td align="center">41/10</td></tr>
<tr bgcolor="#F1F1F1"><td align="center">4.11:1</td><td align="center">37/9</td></tr></table><br>

==Resources==
*[[Gear ratio check]]
*[[Limited slip and locking differentials]]
*[http://www.crankshaftcoalition.com/wiki/Ford_9-inch_rear_ends Ford 9 inch rearends]
*[http://chevellestuff.net/qd/generic_rear_axle_info.htm Generic rearend info] from chevellestuff.net
*[http://www.nastyz28.com/2gcog/rearaxle.html Camaro rear ends]
*[http://www.novaresource.org/axle.htm Nova rear ends]
*[http://www.chevelles.com/years/70/70rearcodes.html Chevelle rear ends]
*[http://corvette-world.com/corvette_1968-82_Rear_Axle%20Ratios_Identification.php Corvette rear ends]

[[Category:Identification and decoding]]
[[Category:Rearend]]