OER Parts offers a wide selection of Brake Components for your 1981 GMC Truck. OER Parts offers 1981 GMC Truck Wheel Cylinders, 1981 GMC Truck Front Wheel Cylinders 1981 GMC Truck Rear Wheel Cylinders, 1981 GMC Truck Wheel Cylinder Retainer, 1981 GMC Truck Drum Brake Bleeder Screws, 1981 GMC Truck Front Wheel Cylinder Repair Set, 1981 GMC Truck Rear Wheel Cylinder Repair Set, and 1981 GMC Truck Wheel Cylinder Pins.