My first year in the rental business (1998) I bought 8 indy trail 488's in West Yellowstone from Two Top snowmobile rentals in the 5000 mile range and ran all of them two more years to 13,000 without a single motor problem. Rebuilt clutches once. The newer 550's can't make 5000 miles without a rebuild. The recent 600 RMK's are also pretty bullet proof.