some minor issues i had were because the stock 50+ yr old pad supports were ..... heavily worn. .... when i did my frame off i bought all new rubber from my local capitol rubber supply. i bought 1/4''-5/16''x 3''x6 feet of hard rubber. i cut two strips about 14'' long and placed them under the cab front where (item 22 [the round rubber] is located
http://www.lmctruck.com/icatalog/ca/t.asp see page=21)

it supports the whole length of the cab bottom support frame where the chassis frame extends outward. i utilized the 1/2'' hole at one end and placed a big rivet to hold the other end. sorry no pics

as that roll never made it thru the camera. It's easiest for you to just go look at your support frame and visualize this & do what you want/can.
i used two rubber squares at each of the 6 locations on the bed support. i also painted the wood blocks. if something is saggin unless the frame is tweeked

everything would plumb to the frame surface.