1972 GMC Pick-up Truck Differential Spool K35/K3500 Pickup - Dana 60 - Standard Rotation - For Use w/30 Spline Axles - Steel - 4.56 Ratio And Up - Front guaranteed to replace your current 1972 GMC Pick-up Truck Differential Spool K35/K3500 Pickup - Dana 60 - Standard Rotation - For Use w/30 Spline Axles - Steel - 4.56 Ratio And Up - Front. 1972 GMC Pick-up Truck Differential Spool comes new OEM 1972 GMC Pick-up Truck Differential Spool aftermarket new 1972 GMC Pick-up Truck Differential Spool of remanufactured 1972 GMC Pick-up Truck Differential Spool K35/K3500 Pickup - Dana 60 - Standard Rotation - For Use w/30 Spline Axles - Steel - 4.56 Ratio And Up - Front.