Ok a year ago (actually a little more than) I replaced my drum master cyl and booster with one from AUtoZone for a 69 Z and ended up getting a correct 309 master cyl. So I'm out in the garage tonight messing with some stuff and decided to remove the check valve because the guy that re-did my trans. last fall told me that they are notorius for causing a hard pedal and thats what I've had with this car ever since I got it a year and half ago. SO I remove the check valve and don't see a diaphram. I stuck a socket extension in there and heard it hit the rear of the booster METAL. I stuck a flash light in there and there is definetly NOT a diaphram in there. EVER HEAR OF SUCH a THING?? Man am I going to go off on AUto Zone here in a mo. when I get this car out. The big problem is when I installed it I had the hood off an nothing painted. Now I have P/S and every thing is nicely detailed.