Pictures of replaced heater core in '81 MH
I took the heater core to an RV place that also works on AC and some other engine stuff. He took measurements and had a new core built and he replaced the old leaky one.
It was a cinch to take out AFTER I realized that the box was riveted to the firewall! I couldn't understand why after taking all screws and bolts off, that the darn thing was still "stuck" in there. There were two pop rivets that I popped out and the whole box came out great. Now to put it back in.
1992 Airstream 300LE, rear queen, Banks Power!