I bought an 04 Titan and when I test drove it I could hear a whine from the rear end. I knew that something wasn't right and the salesman tried to pass it off as tire noise. I still asked to have the rear looked at and after about 20 min the salesman took me to the shop. They had the diff cover off and it was full of teeth. We did some negotiating which included they rebuild the rear. The next day they called and said that they are just going to replace it because it #1 be the same price and #2 they were going to put in an 09 rear end because 04-08 ones were not beefy enough for the torque. I have not verified this, I am just sharing my experience.