Hy Lori's 66, At the risk of being a pain in the butt, your truck originally had a single system master cylinder, and now your going to convert it to a dual master cylinder presumably with a booster, and eventually upgrade it to disc brakes all around, have I got that right? The reason I ask is that if you do only part of the job at a time, you have to use some different components. If you do the dual master/booster while you still have rear drum brakes, then you will have to add a pressure compensating valve to allow the rear brakes to operate with less pressure than the front brakes,[disc brakes require higher pressure than drum brakes to stop the wheels], otherwise your rear brakes will lock up on each stop. You could order a full disc master cylinder and put a residual pressure valve in the rear brake line, but you would still need the compensating valve. I'm not trying to be a pain, I just want you guys to be safe, hope that helps.
