Cletis,,
I went though this as well. My guess would be a cheap casting or poor rebuild of the caliper provided in the disc brake kit. If the kit is from CPP, the part is guaranteed for life. Good luck with that.
I tried to use a caliper off the shelf from a local parts house. The cpp caliper uses a different pressure hose connection thread than the stock gm caliper. So if you are trying to get one off the shelf, make sure the threads match.
