I got mine from Summit. Poly's from Energy Suspension. Lets see if I can remember..
Remove the bumpers (lifting the body will crush the fillers against the bumpers),p/s reservoir (like Earl said also..),the bolt that holds the fuel line to the body in the back above the rear end(line goes from frame to body),tranny linkage (you'll put stress on the pivot). I think there is a brake line bracket that has to be unbolted...?
I used 4 scissors jacks under the rocker panels. Two each side with a 2x4 resting in the channel,full length. Had bottle jacks with 2x6's here and there under the body. Meanwhile the frame was lifted about 1ft,and jackstands placed in each corner.
Did the whole job in the middle of Upstate NY winter in my rented,carpeted garage. Luckily everything came apart with only a 3/8 ratchet. (no rust!)
The body has to be lifted about 3 inches.
If yours are stock,they are probably split and shot. The ones under the door-striker area (position 3)will be missing because GM didn't put them in. Mine had a top part and a bolt,but no lower under the head of the bolt. lol
Body bushings are sometimes called body cushions,in case you Search. Kirbans sells rubber ones.
It took me forever. But,everything is straight and correct. Take your time and do it right the first time. It's not hard. ...just time consuming since I did it myself. No Earl to help.