The flat band up the center of the housing and no dimples indicates a 1957 model 9-inch housing. If it's mounted under the Mustang, then the spring perches would be on 43-inch centers.

The axle on the right would be the stock axle for the '57 rear end. The black one on the left is from some other Ford from at least a 1974 or later vehicle (probably from an 8-inch rear). The center register (the round protrusion in the center of the axle flange) is larger in diameter on '74 and later Ford 8 and 9-inch reads than on previous models.

I see you have Lincoln Mk VII rear discs --although those are definitely not my conversion brackets. With your current axles, you're going to have a mismatch when you go to put the rotors on. The stock '57 axle is going to require a rotor centering ring to take up the gap between the I.D. of the center hole in the rotor to the O.D. of the center register of the axle.

If you can find a matching axle ('74-up) to replace the '57 axle with, you won't need any rotor centering rings.

Last edited by ultrastang (5/26/2014 4:54 PM)

Why is the centering ring needed since the shoulder on the wheel studs seem to hold the rotor from moving side to side and once the rotor and then wheel adapter are installed i can not see how anything could move.I know that the lady who seemed very knowleagable about the spacers and hubcentric and lug centric isues said the spacer did not rely on the center register for strength or support.Not trying to contradict, just trying to lear and sort things out.

Would you have any idea where to even start to look for an axle or specs for the 74 model ford and up ?THANK you Very Much