The calipers on the CPP, Speedway, POL, etc. kits are actually the standard single piston 2wd Chevy truck calipers used up until like 78 or 82 or something. I was buying a rebuild kit for one of mine at NAPA and the guys was like "Why? A new built caliper is only $15" ...or something along those lines. At any rate, it was so cheap that if I hadn't just powder coated my CPP calipers I would have just bought the new one. I think the rebuild kit was around $2.
I have the details written down somewhere around here.
Really the only part you need that isn't standard Chevy is the caliper brackets and the mc bracket. The nice thing about buying the mc kit is that the rod, bracket and stuff is already figured out and just bolts right on.
