MJ Rear Porp Valve...

[Eagle]

I've also got a '93 XJ proportioning valve here if it'll be the best route to go, but I like the idea of the rear brakes still working should the front lose pressure.

That's why the XJ valve is the better way to go.

 

[Bounty Hunter]

The XJ valve will allow the rears to still work should the front lose pressure? I thought this was on the MJ with the dual lines to the rear?

 

[Eagle]

The XJ valve will allow the rears to still work should the front lose pressure? I thought this was on the MJ with the dual lines to the rear?

Remove the dual lines. Run a rear line just like it is on the XJ, from the lower front outlet on the combo valve directly to the rear hose that comes up off the axle. Scrap the second line.

Heck, MJ rear brake lines always rust out where they pass by the gas tank anyway, so this is the perfect excuse to run a new line and avert a potential brake loss. That's where mine popped, and it's where any number of others I know of popped.