3.73 ratio. 4WD. Gear assy. PartQualifier: heavy duty 3.21 ratio. PartQualifier: heavy duty 3.73 ratio. Rear. Differential Pinion Gear. Gear used inside the Differential case that is splined to the axle shafts and meshes with the Differential Pinion Gears. Limited Slip Differential. Side. Center. Drive.