If this sled has the Fuji 488 liquid cooled engine in it, Polaris put these in a million different sleds, so look for one that was wrecked on Craiglist or ebay. The 440 liquid cooled motor will most likely work too, just not as much power (obviously). The cranks are the same on the 440 LC & 488 fan motors. I have 3 of these sleds and they're great, as long as they get oil.
I rebuilt 2 of these. One was an oil pump went bad and the other the crank bearings rusted when a guy stored the sled outside.