This is driving me nuts. I want to walk into Carquest, NAPA, etc. and buy a radiator cap, but without a part number they are lost. It would be a Ford pass-car radiator 1937- 48 (not pickup) with either a 4 lbs. or 7 lbs. rating. Stant or whomever. Any part numbers? Otherwise, it's ordering through Mac's and waiting.