NHTSA Complaint #11673375 — 2021 GMC YUKON

I have again taken my vehicle in for about 8th time trying to get an understanding of why my vehicle vibrates. Again, I was told that the problem could not be duplicated. However, when picking up, I had a discussion with the service manager whom had driven the vehicle as well.. He stated that he felt and heard something from the rear end. I explained that I had the differential fluid change about 2 months ago due to a growling noise when making a left turn. He printed the service bulletin for the differential and put it with my paper. I was told I would receive a call from him the following Monday to bring my truck back in to further investigate because it sounded like the vehicle has a bad rear end. I have not received a call back and have attempted to make contact with service manager twice. My powertrain warranty is almost up and fear that after is when they will finally make a diagnosis of the issue. My engine and transmission vibrates and the whole vehicle shakes when cranking and turning off. This is in addition when driving at any speed. At idle it vibrates and can be felt throughout the entire vehicle. I am afraid that this vehicle is going to stall or fail why traveling with my family. The problem is only getting worst, transmission fluid temperature is starting to rise higher than normal. I am just afraid at this point that I have wasted thousands of dollars on a vehicle and GMC is not willing to fix the problem. I have the L87 and just not understanding with the problems I am having why my truck hasn't been recalled. It was built before 07/2021 when the Arlington plant had to stop make on rear axle drive shaft for propulsion. This truck is a safety hazard. 3rd notice to NHTSA