I have had problems with drive train shuttering issues have taken to dealer 2x for 3 weeks of no answers.
Have they driven it and experienced the shuddering? What do they say?
The first thing I would check is the U-joints. If a joint is bad, it will be out of balance and you will get a shudder.
GM had some issues with vibration in that model. Google “Chevy shake”. Might get some ideas. Might get depressed. Might not be related, if this is something new to the truck and you’ve had it awhile.
If its a vibration, check the U-joints. If you have 4wd, worn U-joints will stress the transfer case adapter and can crack it.
If you are in the 80k miles or greater, your hubs might need replacing. It can happen at lower miles if you have aftermarket wheels with a higher offset.
Are you the only owner? If not, how long have you had it?