Yes, You can run the Steel Shaft from the Chain Drive Assault in the PRO RMK.
The Assault shaft you have is the same on all 2011 and 2015 Chaincase equipped sleds.
The PRO RMK Hexagonal Aluminum shaft on QuickDrive Equipped 2013/2014/2015 PRO RMK... this shaft will NOT fit in the Assault however as it is NOT machined/forged for the oil seal in a chaincase model.
You will also need to trim the rails, run an anti stab wheel kit and run the AVID PowerClaw style 7tooth drivers to run the X3 track.
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