The contact owns a 2023 GMC Sierra 2500. The contact stated that his son informed him that there was a puddle of water in the rear seat. The vehicle was taken to the dealer, where it was diagnosed that the upper track for the rear sliding window was fractured on both sides, causing water to leak inside the vehicle. The dealer determined that the rear window needed to be replaced; however, the part was on backorder. The vehicle was not repaired. The manufacturer was notified of the failure and case was filed. The failure mileage was approximately 21,000.