[cleszkie]

Not trying to insult your intelligence, but make sure you have the NP205 in 2Hi, and not 4Hi. These two are right next to each other in the shift pattern and easy to confuse. If you are running in 4Hi by accident, the front driveshaft will be spinning and can cause vibration and noise in the case. I did this once and could not figure out where all the extra noise was coming from until I double checked the shifter and found I was in 4Hi instead of 2Hi.