Update and greatly improve braking power by converting standard drum brake rear ends to disc brakes. Universal rotor hat ?ts 5 on 4-1/2", 5 on 4-3/4" and 5 on 5" bolt patterns. Caliper mounting brackets weld onto 3" axle tubes. Rotor hats included in these kits will not work with some aftermarket axles. Axles with ?anges larger than 5-3/4" must use cast aluminum rotor hats, ALL42128 or ALL42129.