Can am made that change to the drive shafts a few years ago confusing alot of folks, my guess would be that the splines were to narrow causing them to wear out prematurely, they also got rid of the wear ring on some of them. all the information on them is confusing now for what all is needed for what year machines. i would contact jared puk, Can Am parts guy, he will know what you need for sure and he has great OEM prices. his site has alot of the information in the discription of the parts, ill link it below for ya.