1971 Chevrolet c-10 Stepside. I still regret selling that truck, although it needed a ton of work. Bought it for $300 when I was 15, put it back together (the P.O. had it all taken apart) using a Haynes manual for a guide and a basic Craftsman tool set. Sold it only a few years ago because it was just rotting away and I had no time for it.
The day I delivered it to it's new owner, who breathed new life into it. Completely rebuilt it and it's still running strong as hell on the original straight six, 250ci powerplant and three speed manual transmission (converted from column shift to floor by me at age 16). I miss this truck every single day and wish I'd never sold it!