The rear axle assembly of a vehicle involves a longitudinal, thin-walled tubular housing that houses a differential and axleshafts, to support the vehicle's sprung weight by using vertical locations of the axle housings on the vehicle frame rails by means of its springs that can be coil, or a leaf spring type. Vehicles utilize two designs of rear axle assemblies: Semi-floating axleshafts and full-floating axleshafts with even more robust construction are other types of axleshafts. A full-floating axleshafts do not carry any of the vehicle mass, may be easily pulled off the tapered roller wheel bearings and are intended solely for power transmission to the rear wheels only. On the other hand, there are 'semi-floating' axleshafts which are parts of the rear wheel support system-they not only transfer power, but also carry part of the vehicle weight. In both designs hypoid gears are used with the pinion gear centre line being below that of the axleshaft centre line. Because of this, it is recommended that work on these models be restricted to specific uses, and for any repair or overhaul requirements, the axle assembly should be removed and brought to a rebuilder or exchanged with new or refurbished ones as buying individual axle parts for repair locally has become quite difficult. When replacing an axle unit, it is thus important that the unit be of the same type, as well as have the same gear ratio.