You will be fine , the shredding the titan axle was in the earlier model due not even cooling capacity. ofcourse Nissan put a new cover with fins to resolve this.
so as this is a weakest link, I would buy the truck replace the oil with a qualify synthetic oil, the new ones have the finned cover. . There is also a aftermarket cover that suppose to offer better cooling for extended heavy towing.
But as I have not seen a failure in the past 09-10 model when they fixed this issue you should be good. If it bothers you run royal purple of Mobil gear oil in the rear differential. it a easy change and in 10 minutes you can worry less.