Mark VII rotors will not allow you to run the center cap on 99 Cobra wheels. Go with 94-95 Mustang calipers or 99-04 Mustang calipers. You need the brake lines nad caliper brackets and bolts also.
****If you go with 99-04 calipers you will need a union for the passenger side brake line fo it to fit. ($1.37 at autoparts store)****
Used axles are fine, that is what I used. They are cheaper than new....here is the interchange......
Aerostar '86-91 Rear Axle; Ford, R.
Aerostar '92-97 Rear Axle; R.
Bronco II '84-90 Rear Axle; L.
Ranger '83 Rear Axle; 10 bolt hsg cover, L.
Ranger '84 Rear Axle; 10 bolt hsg cover, 7-1/2" ring gear, L.
Ranger '85-86 Rear Axle; 7-1/2" ring gear, L.
Ranger '87-92 Rear Axle; L.
Note Ranger:::::LEFT SIDE
Note Aerostar::::RIGHT SIDE