General Motors RPO build codes

AG7 6 way Power Seat  

AK1 Custom Deluxe Seat Belts  

AL5 Deluxe Rear Center Seat Belt '67.  

AN7 Strato-Bucket Seats, Swing out!  

Al3 Power Door Locks  

Al6 Power Tailgate Release  

AO1 Soft Ray Tinted Glass, all windows.  

AO2 Tinted Glass, windshield only.  

AQ2 Electric Seat Back Lock Release, '71  

AQ5 Electric Seat Back Lock Release, '70  

AS1 Shoulder Harness, '67+  

AS4 Deluxe Rear Seat Shoulder Harness, '68+  

AS5 Standar Rear Seat Shoulder Harness, '68+  

AT8 Reclining Passenger Seat  

AU1 Electric Door Locks, '70+  

AU3 Power Door Locks  

AV3 3 Point Seat Belts (from 1972 Build sheet)  

A20 Custom seat belts, '64  

A20 Swing Out rear windows, Laguna  

A31 Power Windows  

A33 Power Tailgate Window  

A39 Custom Deluxe front and rear Seat Belts, 66+  

A37 Seat Belt Equipment, '64 only.  

A41 Power Front Seat, 4-way  

A42 Power Seat, 6 way  

A41 Power Bucket Seat, 4 way.  

A46 Power Drivers Bucket Seat, 66+  

A47 Custom Deluxe Seat Belts.  

A49 Custom Deluxe Seat Belts, w/retractors  

A51 Front Bucket Seats, Astro  

A52 Front Bench Seat  

A62 Seat Belt Delete  

A64 Custom Deluxe Rear Seat Belts, '65.  

A65 Split Front Seat w/arm Rest  

A66 Split Second Seat  

A68 Standard Rear Center Seat Belt. '67.  

A81 Head Rest, Bucket Seats  

A82 Head Rest, Bench Seat  

A85 Deluxe Shoulder Harness, '66 1/2 +  

A90 Electric Trunk Opener  

A93 Vacuum Door Locks, '69

D33 Remote Control mirror

D88 Sport Stripe, '70+  

D96 Wide Paint Stripes, * '67+ refer's to body side accent stripe

F41 Sport Front and Rear Suspension, '69+

GS1 2.73 Ratio Axle (from 1972 Build Sheet)  

GY2 *3.31 ratio axle ('71-'72 Chevelle / El Camino / GMC Sprint).

G66 Air Shocks, rear.

G75 3.70 rear

G76 3.36 rear axle ratio

G82 4.56 Rear axle

G84 4.10 Rear axle

G92 Performance rear 3.08

G94 3.31 rear

G95 Economy rear 2.73

G97 2.73 Rear ratio

HO5 3.73 rear axle ratio

J52 Front Disc Brakes, '67+  

JL8 ('69 only) 4-wheel disc brakes

NB2 Refers to:: EXH EMISSION (from 72)  

NK2 Custom Steering Wheel, '71+  

NK4 Sport Steering Wheel, '71+

N96 Simulated Magn. Hubcaps

UM1 AM radio with tape, '70+

UM2 AM/FM with tape

U58 AM/FM

U69 AM/FM radio with buttons.

YB5 General Processing Option (beats me?)  

YE7 *Special Performance "SP" package ('71-'72 GMC Sprint). .  

YJ9 Exterior dress 'emup package

Z10 has something to do with a special hardtop pace car

ZP2 *Trim & color override. This was for cars that had an exterior/interior color or trim combination that was not normally available. This code is listed on the build sheet for a '71 GMC Sprint that was "Classic Copper" with a "Dark Saddle" interior - a color combination not normally available.  

Window Glass date codes: Each window has its own as part of the marking.  

 

 

 

 

''Bellhousing''

Casting Number: The part number cast into the right side near starter.  

Casting Number Part Number cast into the case and tailshaft when made.  

Date code Usually the casting date is in the body but this is the case date. The assembly date is stamped in as part of identifier code.  

When a part is cast, the mold has a part number and a date code set so that it is part of the mold and the part is forever identified. Most older Corvette parts such as heads, blocks, and manifolds, usually have a 7 digit casting number beginning with 3 to identify the part.

Engine Block: On most blocks, the casting number is located on the bellhousing flange behind the driver's side head. The casting number does not usually correspond to any engine part number as the engine part number is for the assembly, not the casting.  

Cylinder Heads: The casting number is usually in the area under the rocker arms. Years of baked oil may fill the numbers to make them hard to read. On some heads, partial numbers were found on the intake runners on the block side, such as the 461 and 462 heads.  

Intake Manifolds: Usually on the rear runner on top.  

Exhaust Manifolds: Usually on the outside of the manifold. Small block Ram Horn manifolds usually have this on your left as you view them. The big block manifolds are down the side.  

Transmission Casting: The numbers are on both the main body and the tailshaft housing, usually on the right side.  

Rear End: The casting number is located on the right side near the prop shaft.  

Water Pump: The casting number is on the front of the body.  

Date Codes and Where Are They?

Almost every mechanical part made for a Corvette has a date code, either cast or stamped into it. These simply identify when the part was made. To the factory, this date probably made sure that they didn't leave any stock laying on the shelf too long, although if you have ever watched any factory production line run, it is doubtful if anyone ever reads the dates. The purpose of the date to Chevrolet was probably to ensure a means to track any defects should they arise. If a part dated March 3 and one dated March 21 were both defective, attention could be paid to those parts built between those dates for other possible defects. Today, these are used to determine if the part is correct for that Corvette, as an engine with a date code of D 16 5 (April 16, 1965) could not be correct for a '63 Corvette as the engine was made after the car was made. Parts too early are usually not correct either, as they would have been installed on an earlier vehicle, such as a B 23 3 (Feb. 23, 1963) in a '67 Corvette. NCRS provides a window of 6 months on date codes prior to the build date of the car. Obviously, a part on a car could not have been made AFTER the car was made._ But given how new items were constantly loaded on shelves, with existing items being shoved further back each time, a part could sit for many months before being assembled on a car. Usually, the parts were used within a few days or weeks but there are many documented original cars that have parts several months old. Be sure to notice that some parts have both a casting and a stamped date code. These can be several days apart. The stamped date code is when the part was assembled and should be the one considered.  

Engine Block: The date code on a SBC is typically on the bellhousing flange behind the distributor. On early big blocks, it was on the passenger side near the pan rail, but later (1970) moved up to the same location as the SBC. Usually the date is given as a letter, a number and then a number, such as B 23 3 which is for February 23, 1963. With any engine still having ignition shielding on, you have a very hard time to see the date. A good flashlight and a wire brush to clean any dirt are a must, even with the shielding removed.  

Cylinder Heads: The date code is located on top under the rocker arms. You must remove the valve covers to see them. Often lead deposits in old engines have filled the numbers and letters so they are hard to read. Often the rockers are in the way.  

Intake Manifold: The small block usually has the date on the driver's side rear runner. The date is typically below the casting part number. The firing order (18436572) is usually cast on the front runner so do not confuse it with the part number. Some big block intakes have the date cast under the intake so that you must have the intake off the engine to see it._  

Exhaust Manifolds: Usually on the outside of the manifold. Small block Ram Horn manifolds usually have this on your left as you view them. The big block manifolds are down the side.  

Transmission Casting: The numbers are on both the main body and the tailshaft housing, usually on the right side.  

Rear End: The casting number is located on the right side near the prop shaft.  

Water Pump: The casting number is on the front of the body.  

Date Codes and Where Are They?

Almost every mechanical part made for a Chevrolet has a date code, either cast or stamped into it. These simply identify when the part was made. To the factory, this date probably made sure that they didn't leave any stock laying on the shelf too long, although if you have ever watched any factory production line run, it is doubtful if anyone ever reads the dates. The purpose of the date to Chevrolet was probably to ensure a means to track any defects should they arise. If a part dated March 3 and one dated March 21 were both defective, attention could be paid to those parts built between those dates for other possible defects. Today, these are used to determine if the part is correct for that Chevrolet , as an engine with a date code of D 16 5 (April 16, 1965) could not be correct for a '63 Chevrolet as the engine was made after the car was made. Parts too early are usually not correct either, as they would have been installed on an earlier vehicle, such as a B 23 3 (Feb. 23, 1963) in a '67 Corvette. NCRS provides a window of 6 months on date codes prior to the build date of the car. Obviously, a part on a car could not have been made AFTER the car was made._ But given how new items were constantly loaded on shelves, with existing items being shoved further back each time, a part could sit for many months before being assembled on a car. Usually, the parts were used within a few days or weeks but there are many documented original cars that have parts several months old. Be sure to notice that some parts have both a casting and a stamped date code. These can be several days apart. The stamped date code is when the part was assembled and should be the one considered.  

Engine Block: The date code on a SBC is typically on the bellhousing flange behind the distributor. On early big blocks, it was on the passenger side near the pan rail, but later (1970) moved up to the same location as the SBC. Usually the date is given as a letter, a number and then a number, such as B 23 3 which is for February 23, 1963. With any engine still having ignition shielding on, you have a very hard time to see the date. A good flashlight and a wire brush to clean any dirt are a must, even with the shielding removed.  

Cylinder Heads: The date code is located on top under the rocker arms. You must remove the valve covers to see them. Often lead deposits in old engines have filled the numbers and letters so they are hard to read. Often the rockers are in the way.  

Intake Manifold: The small block usually has the date on the driver's side rear runner. The date is typically below the casting part number. The firing order (18436572) is usually cast on the front runner so do not confuse it with the part number. Some big block intakes have the date cast under the intake so that you must have the intake off the engine to see it.  

Exhaust Manifolds: The casting numbers on the Ram horn manifolds are on the outside near the 1-3 or 6-8 cylinders. On the big block manifolds, it is found low near the outlet. The date codes on the Ram Horn manifolds are found on the opposite end. On the big block manifolds, the date code is found on the back side.  

Transmission: The Borg Warner transmission has a date cast into the main body and tailshaft in the early T10s. Some later T10s ('70s) have it also. Usually it is found on the passenger side. The Muncie has a date cast on the tailshaft. Unfortunately, these casting dates are the ones that the castings were made, not the transmission. A stamped number usually contains an assembly date. Rear end housingThe housing for the 1963 to 1979 differential has a casting date on the drivers side. Again, this is the case date code. The assembly date is stamped in the bottom of the case on the lip where the cover mates.  

Alternator: The date code is stamped into the housing.  

Water Pump: The water pump has a date code cast into the body in the front but the pulley must be removed to see it usually.  

Carburetor: Most of the earlier carburetors were built by Carter and had an identifier tag attached to a cover bolt. This tag had the part number and date code. On Holley carbs, the List Number is stamped on the drivers side air horn in front along with either a 3 digit or 4 digit date code. The Rochester QuadraJet has a stamped number on the driver's side on a vertical pad

Build sheets are a small strip of paper, about 2 inches wide by 8 inches long or a square about 5 inches by 7 inches that is usually buried in the cotton stuffing of the rear seat, in the backrest of the front seat, or drivers bucket. If you are lucky enough to find this, (the mice usually have other plans for it) then photocopy it immediately and put it back, the last thing you want is to lose it after having it right under your butt for so long. If you make a copy and replace it you are ensuring that the next guy (hey, we all know you plan on keeping this one forever!) can enjoy the thrill of "finding" this original documentation. Build sheets usually confirm what the Cowl tag will tell you, but in more depth.

Build sheets consist of the following information:  

The model number, starts with 1 followed by 4 or more numbers.eg 12467.  

A pair of letters will designate the paint code.  

A three number series will designate the interior.  

A series of one letter and two numbers indicates the factory installed_ options.