PBR Caliper and PAB kitI bought the generic PBR caliper and pad abutment bracket kit from KORE3. It's identical to the GM/C5 stuff from PBR, but without the GM trademarks. I bought the set on sale for a great price, but I think the normal price is still better than buying the separate GM pieces.
Note: I don't know anything about their C5 conversion bracket, and personally would (and did) just stick with the proven Bishop design.