Abstract: A differential gear housing includes grooves into which retaining rings are fitted which engage on races of tapered roller bearings. The width of the securing rings is determined in accordance with the desired tooth flank clearance between a ring gear and a bevel drive pinion and with a desired prestress in the tapered roller bearings. Preliminary to selecting the retaining rings, devices are used which engage with a tensioning bush in the grooves and have a pressure member movable axially inside the tensioning bush and supported on the respective tapered roller bearing race. The pressure member is then suitably moved in relation to the tensioning bush to a position where the desired prestress and tooth flank clearance have been reached. The desired retaining ring axial width can then be read off from the device followed by selection and insertion of the desired retaining rings.