NHTSA Complaint #11677566 — 2024 GMC SIERRA 3500

I'm reaching out for urgent help regarding my 2024 GMC AT4, which is currently at Newby Buick GMC in St. George, Utah, with a transmission failure that occurred on Saturday, [XXX]. While returning from a horse show in Ogden, Utah, the truck began to experience severe transmission issues near Santaquin, Utah, around 5:30 p.m. Just before reaching Santaquin, the truck jerked violently three times-so hard that I immediately checked the camera system inside my horse trailer to make sure one of my horses hadn't gone down. That's how intense the jolt was. I pulled into a gas station in Santaquin and called the dealership right away. At the time, I had three horses on board, it was nearly 100 degrees, and I was hauling a large living quarters horse trailer. The service manager was initially unavailable, but he returned my call shortly and advised me to continue driving to St. George at a steady speed if the truck could manage it. He also warned that it might go into limp mode, and in that case, I'd just be traveling very slowly. My husband was on standby in case he needed to meet me halfway, but I was hopeful that I could make it to at least Hurricane, Utah. I was able to access my GMC app on my phone at the time and confirmed to him that the transmission check light was on, and I was receiving a warning notification on the app indicating there was a transmission issue. I was able to limp the truck as far as Hurricane, where my husband met me. We unloaded the horses into stalls and took both trucks into St. George that night to drop the AT4 off at the dealership. On Monday morning, I contacted the dealership for an update and was informed that the issue was likely related to the transmission valve, and that the required part is on national back order-with an estimated delay of two months or more, but no confirmed ETA. This has been my first GMC diesel. I've always driven Dodge trucks. Over a year ago, I saw the new color GMC released and kept telling my husband how amazi INFORMATION REDACTED PURSUANT TO THE FREEDOM O