Entire vehicle vibrates at various speeds, vibration coming from under seat area of cab source is probably center carrier bearing of drive shaft. Dealer replaced driveshaft at 156miles after confirming problem on test drive. But still has vibration dealer made another attempt at repair then on third time in shop said it was normal. I filed under fl lemon law and manufacturer replaced all 4 tires. But truck still has vibration, it is now much more severe at 13000 miles and I aam still pursuing repurchase under fl lemon law. I think you should investigate this defect as I have first hand knowledge of another truck where the carrier failed such that the repairing dealer told the owner that he shouldnt drive his truck until the bearing was replaced because it could cause an accident. His truck was repurchased by Nissan.

- Davenport, FL, USA