NERVOUS?? Only when you hear a helicopter's over head and the swat team surround your house then I would be nervous. What break in??? That"s Polaris bull. When you buy a new car, truck, motorcycle. Big warning on the dash" rear will make noise till broke in". I think not. Personally im half deaf, and I play the radio almost full blast. It's the people that I gave a ride to that says what the hell is all the whine noise. Maybe it will never be without noise even if it was setup perfect, For one it is the only part of the SS drive train that is NOT rubber insulated and to make matters worse it is attached to the frame right where you sit.
I will play around with it till I find an answer, a complete final drive is just over 1400.00 I did not want to take my unit out and not be able to drive it. Also I wanted to measure everything as it was new. They did make a running change to them in 3rd Quarter 2015 the part number changed. What they did different I do not know. Trying to get and old one also. So I can check them both. I have a bid on one on e-bay it has to be a earlier one being in the 3000 number serial number .