is the truck leaning when u come out to it after its sat for a while? if so your in luck. its just an air bag. while it sounds like a crappy thing its really one of the cheapest and easiest things you will fix on the damn thing. go to gmpartsdirect.com find the rear air sping and order 2 of them. i made the mistake of doing mine one at a time. my first went out at about 40k and the other one went about 2 months ago at 70k. they are about 90 bucks a piece.
its easy as hell to fix. jack up the truck and let the rear axel hang. put some jack stand on the frame. i used a knife and just cut holes in the bags. reach up on top and there is a small plastic tab. push it down and twist the bag clock wise if i recall corectly. twist it about an 1/16th of a turn. and it will drop down. the line is a quick disconnect. push it in to the bag. hold the little ring down and the line will pop off. install the new air line click it in to place then jack the rear axel to seat the bag on the hat. once its seated start the truck up. it will blow up and lift off the jack stands. lower the jack and ur good. there are some good vids on youtube about how to do it. it look me about 15 min my first time.
good luck with the damn thing. i feel your pain though
