my 06 crew cab 1500 silverado has what the dealer calls "beam shake". The frame is made of a lighter weight material and causes the rear end to vibrate when decelerating between 60-40 mph. They say it is not a safety issue so they did not want to fix it, although they have been aware of the problem for years. they recommended putting 300-500 pounds of weight between the tailgate and the wheelwell to reduce the vibration. why have a bed if you have it filled with concrete blocks all the time. After waiting 2 years for a fix, the dealership is going to put a newly modified body mount on. I don't know what the difference could be. My idea, if this does not work, is to put a leveling kit on the front to put more weight on the rear end to dampen the vibration. Anyone else tried to solve this beam shake?