1981 GMC Pick-up Truck Ring and Pinion Set C3500 - GM 10.5 in Rear - w/ 14 Bolt Cover - 4.56 Ratio - Thick Ring and Pinion Set - Fits 3 series 4.10 & Down Carrier - Rear guaranteed to replace your current 1981 GMC Pick-up Truck Ring and Pinion Set C3500 - GM 10.5 in Rear - w/ 14 Bolt Cover - 4.56 Ratio - Thick Ring and Pinion Set - Fits 3 series 4.10 & Down Carrier - Rear. 1981 GMC Pick-up Truck Ring and Pinion Set comes new OEM 1981 GMC Pick-up Truck Ring and Pinion Set aftermarket new 1981 GMC Pick-up Truck Ring and Pinion Set of remanufactured 1981 GMC Pick-up Truck Ring and Pinion Set C3500 - GM 10.5 in Rear - w/ 14 Bolt Cover - 4.56 Ratio - Thick Ring and Pinion Set - Fits 3 series 4.10 & Down Carrier - Rear.