I put a flatbed on my 69 c10. These pics are from immediately after the install. Was planning to build one myself, but I found one for less than I could buy the steel for, so I picked it up. It used to be a welding bed, with a gas generator/welder bolted down in the middle channel and oxy/acetylene bottle holders on the right.
The truck was originally a longbed fleetside, so I did have to cut ~1ft of frame off the back end.
It's not the prettiest, but it's nice for the hauling that I do. I sure don't worry about scratching the paint!
I'll shoot it flat black again at the point when I'm ready to paint my cab and front end.