I bought a 2010 LE Crew CAB 4x4 3 months ago and it has a vibration between 30-40 mph that is felt in the steering wheel. The dealer initially balanced the tires and replaced the rear propellar shaft, but that did not work. They called Nissan's engineers and they suggested installing leaf spring shims per service bulletin NTB07-054b. The dealer installed the appropriate shims and this reduced the vibration but did not eliminate it. The engineers and dealer are saying there is nothing else that can be done for the vibration and that I should file a complaint with Nissan Consumer Affairs, which I've done. It's my understanding that the vibration is caused by the driveshaft binding and that the shims help reduce pressure on the driveshaft, thus reducing or eliminating the vibration. But I'm wondering if anyone has used a suspension lift or different leaf springs to eliminate the vibration?