This is my first thread. I am currently installing a hydroboost system from a 76 c-10 and so far is looking good. I am hoping someone out there can tell me whether or not I can use my original master cylinder or maybe even from a 72 3/4 ton. As the master cylinder on the donor system is preregulated making my proportioning valve unnecessary. I could remove the old p.p. valve but would have to set up switches and wiring for my brake lights.