1973 GMC Pick-up Truck Differential Spool K15/K1500 Pickup - Dana 44 - w/ 30 Spline Axles - Spartan Locker - Installs into standard open carrier case - Front guaranteed to replace your current 1973 GMC Pick-up Truck Differential Spool K15/K1500 Pickup - Dana 44 - w/ 30 Spline Axles - Spartan Locker - Installs into standard open carrier case - Front. 1973 GMC Pick-up Truck Differential Spool comes new OEM 1973 GMC Pick-up Truck Differential Spool aftermarket new 1973 GMC Pick-up Truck Differential Spool of remanufactured 1973 GMC Pick-up Truck Differential Spool K15/K1500 Pickup - Dana 44 - w/ 30 Spline Axles - Spartan Locker - Installs into standard open carrier case - Front.