2010 peterbilt isx 550 cummins noise when cold

So I drive a isx cummins for a week when I leave the yard in the morning with a loaded trailer truck makes a noise sounds like its coming from the rear at first then when I get on the interstate sounds like its coming underneath the cab and I feel a vibration through the shifter and its only when I give it fuel after about 20 minutes it all clears up and nothing the rest of the day temp was about 30 degrees out took it to dealer checked the rear and found nothing also when its a empty trailer it doesn't do it checked air bags also anybody have any suggestions on what it could be?

 

I'm pulling a 53ft van grossed anywhere from 70,000-80,000 when I leave the yard feels like its in the rear but once I get on highway feels like its under cab more towards the front also can a vibration in shifter when it does it then after about 15-20 minutes it all clears up dealer checked the rear and trans said everything was good but its not btw trans is eaton 18 d/o seems nobody can figure it out

 

It's a company truck but I'm the only one that drives it and yes just started doing it when temps were around 30 degrees in the morning the fluid level makes sense cause the dealer checked the rear and trans and said everything was fine and they didn't hear nothing but that was after my shop opened up rear and they probably filled it up to proper level before taken it to dealer getting the truck back this week so we see how it does