I just brought my unrestored 82xxx mile '65 Sport Fury out of a self-imposed 10 year hibernation. I got it running again without much hassle but when it got warmed up the heater core was leaking anti-freeze in the passenger floor. I need to find a source for a factory replacement as this is a factory A/C car and want it to work perfectly. Also, my factory service manual is not real specific on removing it. I am old enough to remember these cars when they were still newer vehicles and Chrysler C-Body cars did not need heater core replacement like the GM and Fords did so I have no experience on them. If I can get it out without any complications I may be able to get my local radiator guy to recreate a factory style core.
This is a 3 owner original black plate 383, AT, p/s, p/b, A/C CA car. 1st owner was for 31 years. I got it from the 2nd owner who bought it from the estate.

 

are you sure its not the heater control valve? that is common. it will all so cause the floor boards to rust and tortion bar anchor to break is best to remove the stock control valve and use an after market one to where any leak is in the engine compartment.

 

I have not had a chance to check that yet. However, I did buy a new aftermarket replacement from JC AUTO right after I bought the car in 1999. Its still in the box. I mentioned yesterday to my wife that I had that part "in stock" and would check that out before trying to remove the A/C box.
I have replaced those in the past and it was not fun then. I'll probably remove the passenger bucket to give me access without causing any back strains from trying to be a contortionist.
Since the car sat 10 years with coolant in it I suspected the core may have corroded but after draining the radiator and seeing how clean it is inside the core I have my doubts the heater is at fault.