hey guys. so i have a '90 chevy silverado regular cab long box k-1500. and my cab is starting to sag in the back so the box and the cab don't lineup and i thinkit looks like ****. so the question i have is has anyone ever had this problem and what is happening to make it happen? and what ican do to fix it so it looks normal again? anything will help out.

 

check the frame rail underneath the truck. I have seen these trucks so rotten, that when they go on a hoist, you'd think it will snap in half