[miker98038]

This is kind of like “what oil should I use?”

First, the master needs to be the same bore size as the oem one. Then did it have (or does the new one have) residual pressure valves. Presuming drum brakes, probably 10# units. Then, can you flare or buy the necessary brake lines to replumb the rears from the front.

I’m a believer in dual masters, having lost brakes with and without them. Scary. Sometimes you toss one in and it works, and sometimes it’s a disaster. Brakes are not where you want a disaster.

Might try the ford truck sites, and see if there’s one that works. If you’ve already done that, just shorten the rod or use an adjustable one. Pay attention to the free travel. I screwed that up once, and the brakes locked up when the underhood heat came up.