Who has Dr. Diff 8 3/4 rear discs?

I'm sure I'm late to the party on this one from the sounds of it. But I am running the Dr Diff rear kit on my Duster and everything appears to be working correctly, WITHOUT a parking brake setup. I have an adjustable prop valve for the line going to the rear, but I am running it at wide open with his 15/16" Master. The car brakes pretty well and the fronts lock up just before the rears.

I have wondered if a parking brake setup was needed to keep them adjusted properly, but I have never used my parking brake on my daily driver to adjust the rear brake pads, so I figured it wasn't needed. Am I incorrect with this setup? I would like to install an e-brake, but have not a single piece of the system currently.