1965 Dodge Dart Charger

If it helps, Detroit Muscle Technology has a nice (and thorough) heater box and firewall gasket kit.

Yup, I got their gasket kit for my firewall and tail lights, very nice stuff!!! BUT....the foam material was different than the original, it was thicker and smooth, very high quality. The original stuff was thinner, porus and rough. May have to make your own or find NOS for a restoration like this one :D

Ulf, do you have any of these gaskets? You could buy the repop kit from DMT and use them as patterns to make new ones, then resell the DMT kit here.