[C10 - C90 Bill]

Generally speaking, I wouldn't hesitate to buy any of the years you have listed but, of course, I would say the older, the little bit harder. Although there is a parts expert on one of the other truck sites I belong to and he seems to be able to find almost anything mechanical.

The one I personally would try to avoid is the '60 to '62 models because of the Torsion Bar Front Suspension, although maybe some others on here can jump in with more info on those particular years.