Here is my story. Had a vibration from day one flat spots on the tires it will go away. Should have real quickly If true.
Went to the dealer and they RFB the tires and replaced several. I had the LS2's the poorest excuse for a truck tire from Goodyear I have ever seen. I pitched a fit about the safety of the tires. They spun very easily and weren't exactly confidence inspiring in the braking department either.
Long story short I returned them to Goodyear and paid the difference for their best tire I think wrangler AT with a Kevlar belt. Much better tire. Pitched a fit with GM too and received a concession.
Felt good at first still vibrated then I had them rotated and balanced again at 6,000 miles felt good for about 50 miles. All this time I was experiencing vibrations over 70 sometimes worse then others like everything got in sync tires, roadway, and whatever and it really vibrated.
In addition I have changed to Bilstein 5100's which is nice improvement in ride and handling IMO. Tried them at their highest setting to level the truck but didn't like the ride of the compressed springs. Settled on one setting above stock and I am very pleased.
So around 6500 miles I am little irritated with the vibration and trips to the dealer are a real PITA where I am currently working.
After reading every post on this board I am ready to try the driveshaft. But since I had the front shocks lowered to one above stock the the steering wheel is cocked slightly to the right which bothers me. The shop did a poor job on the alignment.
So I take it to Parker Tire in Tallassee,Al and ask them to correct the alignment and RFB the tires. They said most of the tires had too much weight. All but one tire was in spec under 25 lbs the other over 32. But the improvement was very noticeable.
I also somewhere in the this time frame torqued my axle u bolts to 80 lbs whiched helped also.
Around 12,500 miles noticed the vibrations coming back some.
Back to Parker for another RFB and rotation which put the one out of spec tire on the back.
Truck is really smooth.
Plus I torqued the bolts to 100lbs and I noticed the truck just felt tighter.
The only time I notice vibrations now are ones I blame on the road surface.
So from my experience I would suggest tightening the u bolts to 100lbs getting a good RFB where they will actually rotate the tires on the wheels to get the best balance.
Changing the shocks might help too.
Also my son had a 2014 GMC CC all terrain with stock Bridgestone tires and never complained of any vibration issues during the 35,000 miles he had it.