On my 63, I'm replacing the body because of extreme rust. I found a donor body that came from California right here in Iowa. The original Iowa truck rusted out from the bottom up due to the salt use in our winters. The California truck rusted from the top down due to the sun baking the paint. The donor body from CA. had the rust through in the roof where as the IA. truck didn't. So I cut the roof off of the IA truck and welded it on to the CA. truck. I just cross braced everything and cut the front at the seem on the inside A pillar. That seem won't be there when done because it will need to be welded up because the inner structure is inaccessable to weld. The rear just requires lots of measuring to get right and then I missed by a 1/4 inch on oneside. I just put a piece of metal in as a backer and welded it all together. I did this with the doors in place so I could get the gap right. For my first time, it turned out great. It's not finished yet, but I went that far with it to see if I could do it or if I needed to find another cab before the project got too far down the road. It requires a lot of patience but can be done,
Scott