I've got a '62, right off the top of my head it has no side trim so you could use any of the other years with some sandpaper work. One of the guys with me at NNL East last weekend sold a box of Chevy pickup stuff that definitely had a bed surround (sides, front wall, and tailgate, molded as one piece). I picked it up a couple of times, but I've got one of each year already and shouldn't get into any more projects...
--Mark