[cheyenne10]

Master looks identical to my original one in 72 C20 with power discs. New one I bought for $18 looks identical (had $8 core also which I got back). Almost certain that is right master for c20/k20 with front Power discs. Your booster looks rough. I know there are services that rebuild these. Last one I read up on required parts to be dipped/stripped of finish and grime before sending in to rebuild. I am still reseaching the competition on rebuilt boosters. I am looking to refinish one I have and replace exterior boots to make look new, no luck on parts source yet. I am just finishing up replacing master and booster with restored one I bought for another truck a year ago. It was on shelf and saved me time finding parts for used one. I will try to restore myslef and use on 2nd truck. I am going to start a post on problems during install looking for bleeding help.

Good luck. Power brakes are way better than manual ones!!