When I put discs on my 55 sunliner I just added a dual master cylinder and plumbed a adapter for the switch and that was it,no residual or proportioning valves and it works fine. Now that I am working on my 37 chevy p/u with the master cylinder under the floor I guess it changes things a bit,the two master cylinders I found at the local parts store with the lines on the correct side are 87 to 96 ford truck with a screw in proportioning valve for the rear brakes and one for a 73 to 79 ford truck that is like all normal master cylinders. What one would be the best to use and what would I need to to to install either master cylinder in a under the floor application. Jeff