My '76 C20! I got it as a C10 with no motor or trans (was a 350/350 setup). Swapped in a 454/ 700R and a 14 bolt floater, and switched out all the front end components to 3/4 ton!
Future plans: stocker cab lights, sliding rear window, lock the rear end, build a winch bumper, get it sitting level and then do a body lift.
It'd also be pretty cool to find a cheap K20 donor truck so I could make her 4wd...