Luck is with me. I found the cap for my radiator on the 74' . The pressure valve is on the tank... not the cap.
Fits Necks with an Outer Dimension of 2.59"
Radiator Cap Shell ( Lebow-Eaton) NUMBER CC-914 O.D.2.90" I.D.2.75" VENTED No GASKET Neoprene FINISH Zinc Plate STAMPING Water