1997-Current Y-car. The differential case must be removed from the rear axle housing for unit repair service. This tool allows the heavy (approximately 60 lbs.) differential unit to be safely removed from and installed into the axle housing. Once the C-clip is removed, the tool is inserted into the groove of the right output shaft. The technician can then safely remove the differential from the axle housing. Once service is complete, tool GM-42155 allows the technician to safely reinstall the differential unit, without damage to the rear axle assembly.