The tag attached to most differential covers may be used in identifying the axle and/or the gear ratio. However, the tag may have been removed during service and not replaced. Then the axle differential covers may be used for axle identification. The number of bolts securing the differential cover, the size and shape of the differential cover, the gear ratio as given on the ratio tag, and the location and type of fill plug are all useful tools in axle identification. Be sure to note all this information before beginning any maintenance or repairs to the axle.