67-72 Chevy/GMC Truck Factory-Air Replacement A/C-Heater Blower Control Switch. This heater control switch is a direct replacement for the factory-air control panel. It is perfect for replacing the old worn out original. Replaces GM part # 3857992 Application Chart: 67-72 Chevy/GMC Truck (with A/C controls) 65-66 Chevy/GMC Full Size Passenger Car