1991 Ford F Series Trucks Differential Carrier F-150 - RWD - Ford 8.8 in. Rear - Yukon Grizzly Locker - 31 Spline - .875 in. Diameter Cross Pin - Rear guaranteed to replace your current 1991 Ford F Series Trucks Differential Carrier F-150 - RWD - Ford 8.8 in. Rear - Yukon Grizzly Locker - 31 Spline - .875 in. Diameter Cross Pin - Rear. 1991 Ford F Series Trucks Differential Carrier comes new OEM 1991 Ford F Series Trucks Differential Carrier aftermarket new 1991 Ford F Series Trucks Differential Carrier of remanufactured 1991 Ford F Series Trucks Differential Carrier F-150 - RWD - Ford 8.8 in. Rear - Yukon Grizzly Locker - 31 Spline - .875 in. Diameter Cross Pin - Rear.