My 2007 avalanche has vibrated since I've owned it. Bought it with 160,000 miles. Vibrated at 70 mph and on up causing the dash to shake and crack also. Put new tires on my truck a few weeks ago just because it needed them and still vibrated so that was not a cause or balance so that's is eliminated. Took drive shaft down to local machine shop to have balanced and my truck runs smooth at all speeds now, they added about a half dollar size weight about 1/8 - 3/16 thick to each end so it was pretty far out of balance and this was never done from the looks of the drive shaft. So I figure it had been out of balance from day one. Issue solved on the 70 mph shake.

 

cool!
good to know :-)