Polaris Ranger and RZR Primary Clutch Puller tool

Good morning, I am new to the forum. I'm 75 years old and love getting ATVs back to usable condition. I particularly like the 2006-2009 Arctic Cat 250 Utility. I currently own 6. The 2006 I am working on only has reverse and low gear. The "drive shaft" in the transmission is completely stripped where the high gear would mesh. Has anyone on here replaced the shaft. I'm told I have to split the case. I was hoping that someone on here could let me know how hard it will be. I already have it stripped down to where the shaft coming in from the clutch side is the only thing left. I was hoping I could just remove the driven clutch and drive it out from there. Directions say different. Any help would be greatly appreciated.

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Just picked up a 2025 Yamaha Kodiak 700 fixing to do a EPI Clutch mod to it since I dropped bigger tires on it !! Air box , exhaust , and programmer next ! 

I have a Harbor Freight tire changer. I could not get the tires off the rim.

Which is more reliable? Shaft or chain drive?