Barn members i learned something today. I never knew that Pressure caps of just about any reasonable PSI is easily obtainable, for our old Fords with the large openings like my 39.I took my radiator to a local radiator shop and was going to have a late model radiator cap neck installed and told him why. He told me about the various caps he had that would fit what i had. dHe was a good honest man. I will know the price of repairing my leaks and the cap in a couple weeks. You should be ab le to get one of these caps at any truck radiator repair shop.