Editing Build it safe

For the benefit of the newbies, or a reminder to the "memory challenged", there are many basic safety issues that should always be observed, whether you build it from the ground up, or finish someone elses project. 
These are common things I see. 

Cotter pins.  
Ball joints, tie rods, spindle nuts and other key components have drilled threads and castle nuts. ALWAYS use new pins. I've seen nails, tie wire?? proper pins cost 25 cents, splurge. 

Flex fans.
If you are going to use them, check them. When they start to crack, toss em. 
True for any fan actually, but the flex seem more prone. 

Brake lines. 
Unless they are factory, or you did them yourself, check em. Aluminum lines need a Double Flare.
Surprising how many people don't know that. If you don't know how to tell, get someone who does. Especially check any newly installed pieces, like around proportioning valves.