One problem related to differential unit has been reported for the 2010 Nissan Frontier. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2010 Nissan Frontier based on all problems reported for the 2010 Frontier.
The rear axle seals are leaking. There is a service bulletin at Nissan for this issue. So this is a known issue. Rear differential fluid is leaking on the rear brakes. This will cause rear brake failure. I think there has been numerous cases of this problem. Nissan best to my knowledge will only take care of this issue if the vehicle is under warranty.