Hy RebelJD, unfortunately there were different heaters in those days, depending on how much money you wanted to spend and what features you wanted and if you purchased it through the dealer or another source. A picture of the heater in question would help us make suggestions if we have any. As to the pressure the core can handle, yes the radiator cap pressure was 4 p.s.i. maximum, but the core may be able to handle more. Age of core and its life up to this point will dictate what pressure it can handle. I have a catalog of cores with dimensions, maybe such a thing exists on the confusilator somewhere?
