My 67, STILL "apart for paint" has 4x disk, they are 73/74 front A body, and Linc Versaille rear. I "lucked out" and just used the stock master, and it works fine
I'm reduced dramatically in strength from arthritic related crap at 67, and cannot stand or walk very far. Even so, with a SB V8 and 727 I could easily lock the thing up at freeway speeds, NO BOOSTER
