I am doing a rear disc brake conversion on my 91 GT. I am going to purchase the master cylinder from a 1993 Cobra, and I have access to the rear disc brakes (calipers, rotors, and brackets) from a 1999 or 2000 Mustang. Will these rear brakes fit/work with my intended setup. I will also be buying an adjustable proportioning valve, FMS plug for the didtribution block after "gutting it", and the 3-2 port kit. Does this set up sound like it will work or will I need different rear brakes than the 99-2000 ones I can get. Nobody at the dealerships can tell me the rotor diameter of these 99-2000 rotors, or the diameter of my stock rotors. Anybody know ? Sorry for the long winded message however I want to be sure before I spend !