One problem related to brake disc has been reported for the 1996 GMC Sierra. The most recently reported issues are listed below.
Seats->drivers and passengers seats (leather) cracked in less than three years. Expected more for the price of this option. Have had brakes replaced 1 - 1 1/2 months prior to failure. I was out in the back country, 40 miles from paved roads, when I heard the rotors being torn up by what was left of the brake pads. It ruined both rotors. I was told at an independant shop that the calipers failed. I went to the dealer and the service advisor insisted that the calipers didn't fail . It was just cheap brake pads. I know for a fact that wasn't the case.