Sorry Steve:
Been busy and didn't look at the computer.
If this is a stock GMC type case then check these areas for clearance:
Stick feeler gauges in there and see how much you can get between the front of the rotor and front plate.
About .008" to .010" is as tight as you want in the front and .013" to .015" to the rear plate.
If the timing is right then rotor clearance should be about .018 on the driver rotor to the driven
and about .012" from the driven to the driver.
This is what Bowers used to have in his catalog back in the day.
I'm sure others can chime in with numbers also.
Remember that if its loose then it wont make much PSI
But if its to tight - Then it galls up and then its junk.
Matt