You can get a master for a 70s 1/2 ton chevy truck that had disc-drum and the valve just make sure that it was not "power"I looked mine up at the NAPA sight just punched in 70 C10 and looked to see what brake sys. was offered if not try 71 and so on tell you find what you're looking for ,I have drum-drum so mine will not help you.Cheaper than buying from on line stores.
Pete
