Does anyone know the best place to get new body gaskets?
Like... fender to header panel and... filler panels to fenders etc. etc.

If I must make my own, what kind of material is this? Mine were so soggy and decrepit that I couldn't even tell.

 

ttt

 

I would think a thin rubber gasket material available at your local parts or hardware store would suffice. The trick would be cutting it so it would fit properly.