" Looking at buying a Chevy Silverado or GMC Sierra? You may be in for a turbulent ride. 

GM engineers can’t seem to pinpoint the cause of a mysterious recurring issue in vehicles riding on GM’s K2XX platform, which includes its full-size trucks and SUVs, a problem that was referred to by one dealer as “The Chevy Shake.” Because GM can’t isolate the cause of the problem, a permanent fix has also been elusive.

 

In December, AutoGuide.com ran a report detailing buffeting and vibration issues found in some GM full-size SUVs after being contacted by an owner who was experiencing these problems. While investigating the SUV issue, another flaw with different GM vehicles surfaced repeatedly in online forums and in the National Highway Traffic Safety Administration’s complaints sections: vibrations from the 2014 and 2015 Chevy Silverado and GMC Sierra. "

 

My theory...

 

This kind of thing occurs when you look at the competition: the Ford F series and the upcoming all new Expedition and Navigator.... you begin to tremble! ( j/k )

 

 

http://www.autoguide.com/auto-news/2016/03/the-mysterious-chevy-shake-is-affecting-pickup-trucks-now-too.html

They found the issue. It was the Ford parts in the shared transmission. 

 

The truth is they all have isolated issues like this yes even Ford.