After three tries I finally got the parking brakes to lock down good every time. I loosened the cable up all the way and adjusted the pads till the drum rotors would barely go on, with a twist. When fully seated the drums are not too tight. Then I adjusted the cable and tried it. Good pedal and the brakes hold the burb on a hill in gear. If your 1999.5 - 2006 GM 1500 isn't holding try this method. When the drum/rotor is off, before you loosen the cable, push the pedal and make sure that the levers on the backs of the hub are being pulled properly and that the actuator is expanding. Then you know the issue is adjustment. Also, the cheap RockAuto parking brake pads work just fine.