Making Gaskets That Don't Exist...

Apparently, GM didn't make gasketing to go between the pieces in the heater assembly.

To me, this is silly - if you don't have it, the parts, over time, will rub the paint off of each other in spots, thus exposing the bare metal to the elements, and the rust begins all over again.

This tar-impregnated cork material comes in a roll from the parts house - I cut the strips to fit. This was placed on all mating surfaces except the lid, where the tolerances wouldn't allow it. I used black silicone there, instead (just gotta do the best you can).

Really works well, and it doesn't rot like rubber or allow for metal rubbing like silicone.