I have the same Dr Diff 10.7 inch rear disc on mine. Here are some tips:
1) the emergency brake must be activated / released 25-30 times or so to ratchet the rear caliper pistons out PRIOR to any hydraulic pressure being applied. If hydraulic pressure has been applied first then rent a caliper tool which rotates and pushes caliper pistons to full seated position then follow emergency brake activate / release process PRIOR to bleeding. Or you can be like me and bleed first and be dumb founded lost not a clue as to why brake pedal is mushy excessive travel hard to bleed ect ect ect.
2) make sure there is some slack in emergency brake cable. This isn't like rear drums where some drag is ok. Pay attention to pass side cable routing to minimize sharp bends. Rear tires should spin without a lot of muscle when car off the ground emergency brake off.
3) rear pads should move freely within caliper mount brackets. You should be able to move brake pads in caliper mount bracket with your hand with no resistance. On one side my pads were excessively tight causing drag, glazed rotor and pads, brakes were squealing chirping. I had to take apart, use mini belt file to clearance caliper mount bracket where pads sit, clearance one ear on one pad, assemble with a film of Disc Brake Grease where pads slide. When done, wheels off ground, I can spin my rear wheels easily by hand.
4) I also removed caliper pins and boots and added a liberal amount of Disc Brake Grease. There was some grease on the pins but not much all. Best to grease those pins up good.
The above were the struggles I had. I will say once all shaken out I am very happy with my Dr Diff 11 3/4 front disc and 10.7 rear disc. And my emergency brake holds car on hills way better then the rear drums ever did too.