[Captainfab]

If you want to add rear disc brakes, you do not want a '63 truck 12 bolt. They have pressed on backing plates. You will want a '64 and up truck 12 bolt. The '64 to early '70 will be 6 lug and the correct width. The late '70 will still be 6 lug but 1.5" wider. The '71 & '72 12 bolt will be 1.5" wider and have the 5 x 5" wheel stud pattern, but will be setup for the trailing arm suspension. The '73 and up are of course originally setup for leaf springs. This is all specific to the C10 trucks. The K5's and K10's will follow the same width changes but will all be 6 lug.

I do offer 3 rear disc brackets for the 5 x 5" and 2 for the 6 x 5.5 wheel stud patterns