you shouldn't have any play/slop in the shaft. if its moving enough for you to see or feel it, i would say its the bearing. i think i have one in bako. i'll check when i get into town tomorrow, or go by the house tomorrow and grab it. there is 2 tcases in the garage on the floor. you're going to have to pull them apart to get the bearing. even a better idea, go to the dealer and get a new one. i'll see if i can get a part # for you.
and before you do all this, make sure you don't have a bad cv, u joints, or slop in the splines. that would all cause bad vibes. i've never seen a bearing on the shaft go bad like that. you usually end up breaking something before you get that much wear, then again, you do drive the thing everywhere so who knows.