Hy VanattiWorkshop, Don't panic, plug the two ports in the master cylinder which are more difficult to reach and plumb to in the truck. Now you can plumb the truck using the primary (the port closest to the pedal) to plumb to front brakes, and the secondary port to plumb the rear system. You can follow the factory plumbing, other than not connecting the front and rear systems. You should not need a proportioning valve for an all drum system. You will have to find out if your master cylinder was designed for drum, disc, or a disc/drum system, if it was for a disc or a disc/drum system you will have to install 10 p.s.i. residual pressure valves in the ports designed for disc brake use, hope that helps.
