Well i just got this back from GM customer service on here, unfortunately they were as useless as I feared.
"Again, we truly apologize for the ongoing displeasure. After extensive review with the dealership and our internal resources, it's been determined your truck is operating as designed at this time. We recognize this isn't the resolution you were seeking; however, please know we've exhausted all available resources on our end at this time. If you'd like to accept our accessories certificate offer, we're more than happy to get it processed for you. Feel free to reach out in the future if you have further questions."
I still need a third visit to lemon law this truck, but I don't want to. I'd lose about $3500 from the xpel, painted bumpers, line-x and i'm quite fond of her minus the vibes. I might try a driveshaft shop for shits and giggles to see if they can balance the drive shaft and effect it at all. I didn't beat cancer to have a new truck handle like this, and be treated like this grrrrrrr