[Warren Seale]

I did mine about 40 years ago. It leaked because of a crack in one of the inlet/outlet pipes. When the car was built, the assembler had the pipe up against the edge of the firewall. The vibration over the years caused the pipe to crack. Be sure to center those pipes in the firewall holes.

I had to remove the inner fender, the glove box, and the passenger side ductwork to gain access to the heater core. You will need to get some new weatherstrip foam from the hardware store. This stuff disintegrates over time.