Which proportioning valve should I use??

80% of stopping is front disk, dont know about drums. the prop valve has a spring loaded piston that takes a huge amount of pressure to push back and uncover the rear brake port. The front 2 outs are for the disk and they are just an internal T, nothing between them. I used one out of a disk/drum jeep and it worked fine. I dont think they are model specific,. maybe more like weight specific? Youll actually increase the tension on the prop valve if the rears lock up. you want the fronts to lock first. I dont think I would ever want the backs to lock and swing around.
Let me clarify something I just learned. The prop valve actually limits the pressure to the rear brakes when it exceeds a set internal pressure dependent on the spring loaded piston. When it exceeds this set pressure, ie. in a panic stop, a valve closes and limits pressure to the rear brakes. Sort of limiting the brake pressure to the rear in a panic stop.