I am about to remove the evaporator case on my '72 and want to know what kind of stuff was used to seal it to the firewall. The plan is to install a homemade case with the evaporator part removed and would like it to seal properly.

I used GE Black 100% Silicone to reseal my box. I am unsure what was originally used. Butyl was used a lot back then.

Strip caulk was used orginially from what I gather. You can get a whole box it of on Ebay for about $14.

Jeff I have a whole box of the 3M strip caulk I bought to do my El Camino. Stop by and I'll give you more then you need.

Thanks, Phillip. I got it done with some caulking stuff in a tube. Now that I am officially retired , some of this car work stuff will be making "progress".