TL/DR summary: Help, my '76 Charger's heater core is a colander and parts availability is non-existent.

Last fall, my Charger's heater core popped while driving to LS Fest East. Up to that point, the HVAC had been working fine aside of the A/C system, which has a hose taped over with Gorilla tape. Having hot ethylene glycol steam pouring from the dash and vents was not a great thing. Bypassed the heater to finish out the season, removed the HVAC unit from the car, cleaned the mouse house out from behind the evaporator, had the heater core re-cored by a reputable shop, reinstalled. Heater worked awesome...for fifteen or so minutes, then the steam appeared again. I'm tearing the dash out of the car in preparation for another HVAC job, and I'm looking at options. There hasn't been an A/C-equipped heater core in the parts system since about 2017, per my investigation. Chances are good that I'll still be dealing with the same rot qualities if I get lucky enough to junkyard one. I think there is a design difference between 1974 and 1975's heater core.

I did come up with a possible option: an E-body HVAC case. They're available. And to my understanding, the 1971-up B-body's firewall was the same as the E-body. As long as the vacuum lines are hooked up properly, what would be the issue?

I'm not the expert here. I'm just looking for a way to improve the drivability of my car. I want heat in the cooler months without the coolant sauna and air conditioning in the summer months so I don't sweat-stain the white pleather seats. And I do not want to put an add-on style A/C system into this car.

You can see the pictures of the original teardown here (mind the PG-13 language): BangShift.com Post: The Charger - The Heater Core Job We Should Have Been Worried About

Why didn't you take it back to whomever did the recore and have them fix the issue?

Solid question. Simply put...I had the car back together, it was Spring, and I wanted to drive it and focus on fixing other issues at the time (fuel delivery, electrical issues, other shakedown items). Once the temps warmed up past 60 degrees out, the heater isn't a necessity for me.

If you don't have a problem with having the "wrong" heater box under the dash, just call up VintageAir and get a new "wrong" HVAC unit to install. It's half the size if that and the box can be purchased separately as you already have the under hood stuff. There are other companies as well that sell the hvac boxes.

Kevin

if the tanks are good, Might try Glen ray there shouldn't be any black magic to replacing the core other using a quality source

Absolutely no sense in inventing problems. You should take the core back to the guy that fixed it and have him test it. Or else send it to someone that can re-core or fix it correctly. To me that's the simplest and most cost effective fix.