So while I wait for my wheels and tires to arrive, I have been looking further into this machine I have. I see that the factory installed 400's in some models. I can't see where the factory ever originally sold them with the 440. I am assuming at some point, it was discovered this 440 could be adapted quite easily (by the looks of things) as a replacement. Is this correct? If so, where would this 440 have come from? (I.E. snowmobile, etc.)