[Stocker]

Not much help, I know.... more than 20 years ago, pre-forum, I replaced the heater core in my A/C K20. It was quite quite a pita as I recall, but I did it and hope I never need to do it again. I'm just a general maintenance with basic hand tools in the carport guy, so it can be done by just about anyone with determination. But it's no fun.

FWIW, I have heard of problems with aluminum heater cores, and brass is preferred. No specific info though, just a memory of something I saw somewhere.