wiper seal???

Iv always heard they dry out and thats why floor rust out what does this seal look like and exactly where does it go?

Hunk of neoprene-type material. Also a foam gasket at the pivot mount.

I usually just buy new seal kits from Schumacher Creative Services. They are cheap and come with instructions.

Water from under the dash? Are you sure it's the wiper pivot seals? I replaced them on 3 different A-bodies and every time it rained I still had water coming out from under the dash. Leaked really bad! So I know it wasn't the wiper pivot seals.