Jerry,
I am in the same position as you. My '63 C-20 needs the same repair. I took it to a body shop where I had bought a $250 gift certificate at a charity auction. I wanted to see how much it would cost for them to do the work. It was of course, well beyond the $250 and about three times the amount I had been given in Washington state. (This is Alaska!) They did tell me though, that I could do the repairs with the cab in place which would keep it from twisting when it is all cut-up, and makes it easier to fit when bolted back on. Has anyone else done that, and if so, are there special problems I should be alert for? (I should mention this body shop has a reputation for quality work on classic cars, I know the owner, and I think it might be possible to use my gift certificate for professional pointers as opposed to having them do the work. I just don't want to abuse my relationship with them by asking for too much free help.)
Keith
