I have the cpp kit on my 59.
12 inch disc original 6 lug hubs. The disc sits on the "back side" of the hub. I'm not sure about the after market hubs.
Patience young grasshopper. It is entirely possible cpp has screwed up on your order. Many of us have been running the cpp brakes for a number of years. My only complaint about the brakes is bearing life. The instructions weren't all that good either, and some reworking of the master cylinder mounting bracket was needed for proper fit.
Once fit to your truck, and adjusted, the brakes do amazingly well. I understand your frustration. Take a deep breath, and get collected. As the saying goes... "Don't cut off your nose to spite your face!"
John
