I have a 2006 GMC Sierra, and have had it in the dealership 6 times for front end noise and vibration in the floor, they have aligned it, they have changed out the intermediate shaft twice under a service bulletin, they put four new tirs on it, truck has 16997 miles,i am not the only one that has this problem, GM has bought some of these trucks back, any info

I had the exact same problem in a truck I bought that had 60,000 miles on it. I installed new tires, alignment, new brakes and machined rotors, all with no luck. I also went as far as trying to analyze the problem with vibration equipment from my work, again with no luck. I took it to a garage where they put it up on a hoist with all 4 wheels in the air, and they couldn't pinpoint the problem. Eventually the garage ended up putting a new front axle in the truck and the problem was gone. The problem is inside the front axle, possibly bearings or the initial setup itself. The axles are not worth tearing down yourself because they are worth about $1200 and only about 2 hours to install a new one. If you are under warranty, do not let this go. I have taken this truck to Florida from Ontario with the new axle, no problems, and have since added about 30,000 miles and it's working good.