a net shape is produced with the additional step of machining the inner surface as is required of a cast housing a near net forged or cast preform may also be used and the net shapes formed over the chuck in the same manner a detailed above during the forming operation the housing 12 is plasticized which minimizes spring back and allows a high level of dimensional accuracy the outer contour of the chuck is imprinted very precisely into the inner surface of the housing 12 the outer surface of the housing 12 is only free formed by spinning rollers therefore the outer surface may have a wavy shape which does not adversely affect the operation of the differential assembly 10 in the case of spin forming in general there is no deliberate change in the wall thickness during the forming process the starting workpiece is a sheet metal disc preferably the sheet metal disc is not entirely bake hardened in order to facilitate the formation of the housing 12 however it may be desirable to bake harden the surface of the sheet metal while not bake hardening the inner thickness of the sheet metal in the case of flow forming there.