The brackets to mount the motor look different on the AXYS... but the starter motor, shaft and bendix are the same... The clutch has a diff part number.. but that is because the AXYS has a better angle cut on the sheaves... something that can be corrected at the better clutch shops like Cascade or Indy.
Battery box is diff on the AXYS compared to the ProRide... but just get the lightweight one from Rich Racer on the forums here that holds a lighter battery.
As for the solenoid etc... should not be an issue to make it work.
For those thinking of buying a "Take off Kit" remember that a new, Complete, Primary-clutch is included when you buy the kit from Polaris... so a full Take-off kit would only have a value of around $100 -$150 WITH a swap for the ES clutch. (you trade clutches)
It is NOT possible to add a ring gear to a non-ES clutch.
Check out this thread on "Take off" ES kits ... buying and selling information.
http://www.snowest.com/forum/showthread.php?t=349121
The part number for the new Axys Electric Start Kits is 2881243 for the RMK models. Retail on both kits is 639.99.
Figure 10-20% off that from a discounter .... Sell your stock primary-clutch for $400 while it is still new... and a full ES kit for an AXYS-Mtn sled would only cost you around $115-$175.... Not bad.
.