340,440,488,550 fan engine interchange

[Bushwacker1]

Would like to know what the differences, and similarities are between the Polaris340,440,488,and the 550 fan engines. Is the motor mount bolt pattern the same? Could you take out a 440 and replace it with a 550 and have the clutch placement correct without making any modifications? Was the 550 built off the same cases with a different size bore and stroke? Where does the 488 fan fit into the evolution of these motors? They all look very similar so if anyone has swapped them back and forth please share your experience.
Thanks

 

[treemagnet03]

I know the 550 and 488 are related...and if I remember correctly the 488 was based off of the 438 (440). However, I am not sure the 338 (340) is related. That would be rather a stretch I would think? There is at least one person on here with a 550 in a 340. Just search this section and bit and you will find him...he should be able to give you the low down on the info...