I’ve read that 67 p/s control valves are a 1/4" small nut, and they went to 5/16" in 68. What do I measure to see what I have? The outside diameter of the metal end of the hoses between the control valve and power piston are 5/16" but I can’t get a straight answer.
If the tubing OD that goes into the nut measures 5/16", you have the 5/16" fittings with 1/2" nuts. I believe only the early 67’s used the smaller 1/4" tubing with the small nuts.