I'm getting ready to hang the heater on the firewall of my new cab. I noticed that they used some sort of gooey, black sealant along the joint between the firewall and heater along the top to keep water out. Anybody know what this stuff is or what the best thing to replace it with would be? I'd like to use something that would also be good for the transmission access plate as well.

 

Eastwood Co. - 3M Flexible Strip-Calk 20 yds in 60/ 1' lengths

This stuff works great.

 

And you can try automotive body supply stores for it also. That is where I got some.

 

Thanks, guys. I'll give the local auto body supply shop a jingle on Monday.

 

I also used this stuff to seal a leak up near the heater, as well as all around the third brake light on the top rear of the cab. No leaks now. This is way better than any RTV.
And it is easy to clean off if need be.