your toro two-stroke should be a tecumseh 5 horse...it should have a 3/4 shaft, so dave31's right to suggest the centrifugal chain/belt clutches,3/4 is a common size, cheap stuff.the only thing is most centrifugals engage around 2000-2500....what would the toro-two-stroke spin at idle...would it eat up/burn out clutch shoes quick?. maybe set it up like it probably was on the snowblower, with a tensioner pulley and belt drive for the gear reduction and clutch, going to a jackshaft, then to the rear wheels. or go get a COMET 20 SERIES, with a 3/4 driver.your tecumseh/toro should have 4 bolt-holes around the shaft, that protrude about a half inch.these will fit directly to the torque-a-verter comet kit.you can find the kit for around 150.ebay, go-kart sites, theres alot of competition selling these, so a better deal is always there. then you won't need a clutch, or gear reduction, or a bunch of ugly bootlegged crap.comet cvt's are beautiful things, i dont know why i dont see more builds with the 20-series.its adaptable to MANY different brands. these are no bull, they've been around for 60+ years. honda civics even had a CVT trans at one point,1995-something. anyway i have a couple tecumsehs like your's, they sound like dirtbike engines. just take the carb off, take the four phillips screws out of the flat side,take that cover off and theres your diaphragm, snowblowers dont have air-filters, so its probably just dirty.dont tear the diaphragm though, get the cover loose, then use a razor blade to scrape it off, if it feels stuck.might avoid a rebuild kit that way.