This might sound strange, but where is the rad cap? Maybe a better question is "How do you get at the rad cap?" The rad is completely hidden under the front panel, and only visible through the grillwork. I've been having heating problems (seems to be common with these cars), have had the heater core flushed (no change) and read a suggestion to keep topping up antifreeze and to change the rad cap.

there is no radiator cap, the only place to fill the cooling system is through the resevoir cap