1979 Chevrolet Scottsdale Stepside
I bought this truck for $800 barely running, and needing pretty much everything done to it to make it a driveable truck again, I replaced:
engine, transmission, transfer case, front driveshaft, front axle, half the cab floor, rebuilt 2 body mounts & repaired 4 others, fabricated both bumpers, completely re-wired the entire truck, fabricated new exhaust, repaired door bottoms and rocker panels. In the end this thing was awesome to drive and got 16mpg.