Im working on (2) 80s trucks adding factory air to them, that came from the factory without.
I was able to make 2 good heater plenum boxes out of 3. The 3rd one had huge holes in the casing, either from rough handling in removal or else from storage. Between the 3 heater boxes I was able to get 2 each, good evaporators and heater cores. On one of the 2 good units there was a hole in the lower box casing, not that would have really kept things from being functional or anything.
But I cut the edges of the hole out to even things up and then cut a matching patch out of the "parts" heater plenum box. I then JB welded the patch in from the inside, and just the seams on the outside and ground/sanded that down so it's barely noticable.
I bought the "mega" heater box rebuild kits for both from DMT, but they didn't come with the foam for (I think it was) the blend air door.... There's 3 doors within these heater boxes. The foam on the same door was shot on all 3.
I went thru all the choices of foam from McMaster Carr and "guessed" the best I could as to which foam sheet to use. I bought (2), 12x12 squares of foam, I don't remember what I ended up using but found out later there would have been maybe a better choice but what I used worked fine as was. One characteristic I looked at was resisting mold, resisting actually like a sponge and soaking up all the moisture present on every AC system. I stripped all the old foam off the door and re glued the McMaster Carr foam into its place. The door out of one of the heater boxes I had here, wound up unusable. I basically had 1 of everything that was junk/ unusable out of the 3 heater/AC boxes I had to start with. I had "just exactly enough" good pieces out of 3 heater boxes to get 2 good usable ones.
Side note
When looking at DMT's site looking for the parts I'd need, they had a long paragraph about "not" having the foam that lined the doors within the heater box, and that it was a common question of customers, that they were looking for this particular foam. IDK if that appears on other sections of their site pertaining to parts for different vehicles than I'm working with... But thought it was important to put that out there for those other members that may have the same question/issue with theirs. IDK what the differences are in a heater box for what I'm working on vs those for an a body as it's been 30 years since I did a heater core on an A body and had an a body heater box apart... I've slept since then, and have a little bit of CRS on that subject haha
