Interesting you mention Ford in that context. When we were poor college students in the 1980's, I had bought my then wife a '65 1/2 Ford Galaxie 500 that ended up having a leaking heater core. All you had to do it was disconnect the hoses, remove a cover and pull the heater core straight out of the firewall. Unhappily, that core was also made of unobtanium at the time and I couldn't get a replacement for it. Gave me my first experience with JB Weld. lol.