my denali makes a noise when driven long distances on 2006 GMC Yukon XL Denali

this is not the usual pump or air compressor sounds like a jack hammer and happens off and on when driving long distances..we have had the suv at the local gmc dealer twice and they have it for almost a month and could not figure it out..this started happening after a new set of tires where purchaed and we did discover that a tire sensor had been broken in the process and after this was repaired we thought the problem was solved but after a few weeks the noise returned..any thoughts on the problem would be the way in the process the dealer did replace the shocks they were leaking and they thought this was the problem..also my wife claims the problem does not occur when using the cruise control.

Asked by for the 2006 GMC Yukon XL Denali
4x4 system is, intermittently, 'trying' to engage without activation! Resulting in gear tooth clash or grinding while not fully engaged. While this is happening, it would be a pretty loud roaring noise that should change as your speed changes. Has the 4x4 module been scan tested?
This is just my guess! I may be way off but have seen it before!
this is not a roaring noise and it does not change it sounds like a loud pump noise and this suv has awd I believe