Two different types of shafts have been used: the tapered shaft and the flanged shaft. The differences are obvious. The terms, tapered and flanged, refer to the outer end of the shaft. The tapered shaft has a single retaining nut on the outer end of the axle shaft. The flanged shaft has a mounting flange for the brake drum on the outer end of the shaft and the shaft is held in place by a retaining plate. One other important point: some tapered and flanged axles have an inner oil seal fitted in the axle shaft housing, inboard of the bearing; some do not. If your axle does not have one, don't install one when replacing the bearing! Axles with an inner seal rely on chassis lube for bearing lubrication and must be prelubed prior to installation. Axles without an inner seal rely on differential oil to lubricate the bearing.