godtool

I searched this site and found a guy that had a smilar problem but he did not say what the final fix was. This is my story

I took my 2003 Silverado 3/4 ton 4x4 to the Chevy Dealer in town yesterday to fix a vibration\noise. They figured it was u-joints so they replaced both rear driveshaft u-joints and the vibration\sound is still there. It tends to vibrate after 90 km/h. Its a fine vibration you can detect through the steering wheel but it is most noticeable as a driveline vib. (I think) and is accompanied by noise also. My driveline is the 6.6 Turbo Duramax with 5 speed Allison. It only occurs when you accelerate up hill or even accelerate downhill and again only over 90 km/h. The vib\noise is gone when idling along or coasting. I have over 150,000 kms on it too. When I took it in I thought it may be the turbo or loose exhaust or a wheel bearing, maybe a cv? The cv's do turn with the wheels in 2 High, no locking hubs. Its also a single piece driveshaft. It has push button 4 wheel drive so in 2 High the front driveshaft does not turn (diff unlocks) I had one wheel bearing on front changed last winter. Maybe ther other wheel bearing is going but when last wheel bearing went vib\howling noise was way less. I'm thinking they would have already checked the wheel bearings and cv's. I wonder if it could be a tire? Would not they have checked the tires too??