Auto body repair & detailing: vinyl roof, mustang ii, vinyl roof

Question
I purchased a 76 Mustang 2 all original for $400. Its in great shape but my mechanic told me the vinyl roof is responsible for the ton of rust in the roof. Is there somewhere I can purchase premolded panels to weld in place? Also what is a lead seam?

Answer
Body solder (lead tin mix) is what the car makers and body shops used to use to fill imperfections, the seam at the quarter panel to the roof was always a big one. As far as the Mustang II goes, there are not a lot of after market parts out there for that car, not a very desirable for restorers. You can rip of the vinyl, clean up the rust an d fiber glass it.