Rear disc Brakes on 8 3/4

I have his bracket kit and am super pleased with it and his service! My 8.75 is sitting on a homemade stand all assembled waiting to go in the wagon.

EDIT: and 14 inch Magnum 500s fit my combo which is his adapters and the 2000 base Mustang calipers/rotors - don't know about 14 inch Rallyes or steelies.

Found this thread, and am interested. I have a stock 8.75 rear with small bolt pattern and 14" Rallye wheels. I would assume the brackets will fit just fine and the rotors will just need to be drilled to small bolt pattern? I really don't want to change to BBP, since the front is all rebuilt and ready with discs.

Can you measure the inner diameter of your Magnum 500's and I can compare to my Rallyes.