rear disc master cylinder upgrades

i currently have dana 44's on an xj with chevy disc's in the front and explorer disc's in the rear. I have not changed the proportioning valve yet. which jeep can i steel one from? i've heard 03 rubicons might work. Is there some larger master cylinder that will push more fluid that fits an xj?

Rubicon or Grand cherroke 98 vintage will work for your valve or you can do what I did and that is to cut the spring in the valve to decrease the proportioning to the rear. It makes the rear stop harder assuming thats what your rig needs.Dodge Dakotas use a larger master cylinder and you will find some good write ups if you click the search tab.