My bike was a demo that the dealer used after the Browning edition he was going to use was making a noise that he thought was the gear case. He called Polaris & found out that it was a bad batch of axels that were used & they sent him 3 new ones & 2 of them were bad. It was fixed & works great now for him.

 

I don't think the problem is inside the rear gearcase, but that is about where it sounds like it is coming from when you are driving it. With it in park, if you get behind it and push and pull it to get it to rock back and forth, you can actually see the rear cv joints moving around and hear the same clunking sound. So hopefully recplacing that in the rear should fix it.

 

From looking at mine and the parts breakdown there are a couple things I see that could cause the play in the stub shaft where it goes into the case. 1) The gear case side bearings are made with too much play. It looks like the diff uses a 1 piece ring gear and carrier assy. It is supported on each side by a ball bearing and the axles slip into the ring gear's splines. The bearings that support the ring gear must have VERY little to no play. If the ring gear is allowed to move around AT ALL it will wear EXTREMELY fast. Ring gear and pinions are precisely machined parts and require precise assembly and must be held in precise positions. We are talking thousandths of an inch of leeway. If the ring gear is moving as much as the axles move it will not last long. That would also explain the new more expensive bearings. Another possibility is there is nothing at all wrong. If the stub axle's splines are just moving inside the ring gear it may be a non-issue although even if it is spline play, it does look a little excessive to me.