The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, there was an abnormal clunking sound coming from the rear suspension. The check engine warning light was illuminated. The vehicle was taken to the dealer, who diagnosed a failure with the rear suspension. The vehicle was repaired, but the failure reoccurred 4,000 miles later. The contact stated that while reversing, the contact heard an abnormal clunking sound coming from the rear suspension. The contact also stated that there was also a strong antifreeze odor permeating the interior of the vehicle. The vehicle was taken back to the dealer, but not yet diagnosed. The vehicle was not repaired. The manufacturer was notified of the failure, and a case was opened. The failure mileage was 38,000.