Had 4 new tires put on Cecil the other day. As soon as the rear tires came of, my mechanic commented, "Yep, typical GM rear brakes". The rotors are rusted, pads are ok, terrible noise 50% of the time when brakes are applied. He, off the top of his head, estimated $350 to replace both sides. He will probably use local parts, ex. NAPA. Looked up parts myself, brakes are easy, going to cost about $300 if I do them. Calipers, rotors, pads.