GM rear drum to disc brake conversion kit is designed for 10 and 12-bolt rear end with staggered shocks and C-clip axles with 5 x 4.75″ bolt pattern. Includes; two 10.5″ vented rotors, two rear cast iron brake calipers with built-in parking brake, two backing plates, mounting brackets, brake pads, and all the mounting hardware. Won’t work with C-clip eliminators.