The conversion kits do not fit the tractors that had Onan engines in them. The 317 tractors are bad for the driveshafts going out on them. When replacing the engine you need to evaluate the driveshaft. If there is any play in it at all, it will cause the main bearing of the engine to go out, which would not be covered under warranty. The driveshafts typically last 1000-1200 hours.
