I am going to assume that since your car is a 71, you are referring to the Kelsey-Hayes 4 piston setup your car should have. On my car I used a manual disc master that is correct in application for a 69 Dart. Included is a picture of it. The manual 4 piston master has 2 equal sized resevoirs, where the newer style single piston calipers need the larger resevoir as shown by greendart72. I'm not saying that you can't use that one, but according to the person who I get my brake stuff through, the correct unit for a Kelsey-Hayes manual disc is the one I have pictured. If you'd like, I'll pass you his number, he really knows old car brakes.His name is Craig Studnick, and his number is (516) 485-1935. He is a little unorthodox, but he really knows his brakes. Hope this helps, Geof
View attachment 101983