after sitting many years I decided to rehab my 1st and oldest ariens 21 model 911. its at least 30 years old . I bought it 25 years ago with a sick tired Tecumseh 5 hp and repowered it with a kawi fc150v and used it commercially for a few years. the drive needs some new parts and they are still aval so I tore it down today and ordered new axel bearings and retainers. very interesting desighn . its like they tried to improve on snappers drive system . parts are not cheap tho. def a learning curve to work on these . these are very versatile mowers and the only other mower besides snapper hi vac that can suck up yard debrie.very usefull in my biz.