It was the calipers. Did a quick test before replacing the calipers, simply turned the rear wheels (with tires off) and they turned. Applied the parking brake and they would not turn. Also inspected the old rotors for any signs of a problem in the drum area. After replacing the calipers did a test drive and no issue. I will drive it 500 miles this weekend and will be looking for issues.
A few notes. A 10mm wrench is required to bleed the rear brakes. The auto part stores make a special wrench, but it is to long/ Simply use a small 10mm closed end wrench. Bought the calipers from AutoZone. Big mistake. Drove 15 miles to Autozone, bought the calipers and inspected them when I got home. Both calipers were tampered with and although they were the same model, they were not a matching pair. I called Autozone and they stated they were the last two and to go to another Autozone. I drove 30 miles to the next Autozone and the puleed two more calipers. They were not matching sets either. 4 rear Bravada calipers and none of them matched sets (all four from different rebuild shops and all four from different GM generations for this caliper). Two of the calipers were remanufactured so badly that the brake line bolt could bot be inserted without stripping the threads. If you buy calipers from Autozone I suggest inspecting them prior to purchase and to bring along a brake line bolt to confirm it does thread.