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. 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). 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.