Auto body repair & detailing: 1992 Chev P/U Doors sag, gmc trucks, gm dealer

Question
How does one go about shimming or lifting the sagging hinges on Chevy doors?

Answer
your hinge pins and bushings are worn out. That is really a job for the professionals, it requires a spring compressor, the ability to take the door on and off without damaging it or the paint on the fender, and it requires the ability to drive out the pins and bushings. If you feel you can do this, bushing kits are available at parts stores everywhere, including your local GM dealer. I have installed hundreds of these kits, they will have them in stock if they sell CHEVY OR gmc TRUCKS. The hard part is compressing the spring to re-install it. Without it, the door won't stay open. It is part of the check link cam assembly. You absolutely cannot get the spring back in without a compressor. You can use a floor jack and a helper to support the door when it's removed, and to hold it while you pound in new bushings. I really suggest you have it done professionally, however. A lot can go wrong here, and if its a decent truck, you don't want to beat it up.  Bill