Have you checked the bolts on the transmission mounts. They have been know to work loose and even fall out.Clinsta said:I've got an 05LE 4wd that at around 80,000 started vibrating at 75 mph. This isn't just a small vibration, it has things in my dash behind my gauge cluster rattling. The dealership blamed the tires. I did the tire balance and rotation thing about four times. Still have a vibration. I got it up on jack stands put in drive and got it up to 65 mph and I could hear a shuddering sound coming out of the pinion area of the rear diff. and I notice that my u-joints had a little play in them. I was hoping it was just the u-joints, so I replaced them. Still have a vibration. I went to the dealership and got a new pinion bearing and replaced that. Still had the vibration. One of the techs at the shop said he could see the drive shaft was a little out of round so I bought a new drive shaft and replaced that which happened to have new u-joints.... of course. Still didn't fix it. The shop manager said he thought it was a bent axle on the driver side. Replaced that and didn't fix it. So far I'm over $2000 in on this and still have a vibration. I just rolled a 100300 on the odometer last week so I'm at a point where I either fix the problem or sell this truck for way less than I owe on it and buy another truck. I still like my truck and I don't want to have to get rid of it. So I went back to the dealership and brought up the rearend gear issues so many people have had, the shop manager said that to replace the rear gear set, they would have to replace the whole rearend... axles, axle housing, everything. That is going to cost over $2100. Is this my only option? Does anyone sell a rear gear set for a Nissan Titan?