We have had rwa failures due to lack of service. Once a year jack up the rear wheel, check the brg. play. The early AC rwa's use different thickness snap rings to set clearance instead of tightening a nut like you SHOULD do on a 2wd. Failure to do this lets the straight cut gears pull on an angle and will fail them. This is especially important on older machines! Check em out. Parts are high $$ to fix and used ones are impossible to find...