someotherguy
Truly Awesome
GMT400 C1500 is 5x5.Apparently, you have a C1500, since this kit is for 5-lug axle shafts.
I thought GMT400 C1500s used a 5 X 5 1/2 bolt circle. These rotors are triple drilled for 4 1/2", 4 3/4", and 5" inch bolt circles.
For a thousand dollars, you could swap rear axles, get 11.x Duo-Servo rear drums and the much-stronger 9.5" ring gear axle assembly; and spend the rest of the thousand on 5-lug axle shafts to keep your existing wheels. Or spend a little more and get front hubs with 6 lugs, and 6-lug wheels.
You'd eliminate all the disc-brake conversion problems, probably have stronger rear brakes than the 12" rotor aftermarket kit, and retain OEM parts compatibility.
Richard