[Sparky73]

Everyone has posted great info and great links, but from reading a couple of threads, here are the numbers I got. I cannot find EXACT numbers, so use the information and use your best judgment as well. I also agree that car is pretty rotted, but if anything.. practice on it! If you feel like attempting the job, go for it! You'll never learn unless you try.

Floorboards: 22g (20g is used often, but it measures 22g from the factory)
Rocker Panels: 20g (18g can be used. No real noticeable difference in thickness and provides a little more structural support. Will be a little harder to shape though.)
Fenders/Body: 22g

20g is a good 'multi-purpose' size and could probably be used all over if you don't want to purchase a bunch of different thickness's. I also read that the earlier models may have used a thicker steel, but I have no proof.

HTH, Jon