Since I couldn't find a new oem one, and don't want to try to track down a used one, I plan to run one of these in my '75. Mojave Universal Heater
You guys don't have a GOOD radiator shop around you eh? There are several around here that will recore any heater core for way under $100.
i got the core out of my 73. i can check and see if its good. if so you can have it, just cover the shipping
i filled it with water, no leaks. here's some pics to make sure it will work. for reference it came out of this housing
looks and sounds good to me....just let me know shipping to 37804 and i can send it paypal...thanks again Tony