What are some common problems with 4x4s?

[Chevy350V8]

Im looking at a nbors 76 gmc 4x4 (I know I druled to) haha but He said it didnt have a front drive shaft, and something else (Im sorry my memory is not good ) But what are some common probs with these trucks? It needs some body work but its actually a pretty solid truck. I got some pics that I attached. Sorry there not the best. And It will need a total interior rework. And whats a good offering price? I can get more info if needed. It has a 400sbc with 350 trans, with 96k on speedo. Needs tires, dual cherry bombs, he said he forgot the lift that it has, and Its been sitting for six years. (I know i should prob stay away but Im addicted ). Any help will be awesome. Thanks guys