Update and greatly improve braking power by converting standard drum brake rear ends to disc brakes. Universal rotor hat fits 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 will not work with some aftermarket axles. Axles with flanges larger than 5-3/4" must use cast aluminum rotor hats, ALL42128 or ALL42129. Kit includes rotors (.810" x 11.75"), universal rotor hats, rotor bolt kits, caliper mounting bolts and caliper mounting brackets for GM intermediate metric style calipers (ALL42083 and ALL42084). Kit Does Not Have Provisions For Parking Brake