The contact owns a 2019 GMC Sierra 1500. The contact stated while driving at approximately 20 MPH and making a left turn, the vehicle shook violently. The contact stated that no warning light was illuminated. The contact stopped the vehicle and turned off, and restarted the vehicle. The vehicle was restarted, but after shifting into drive(D), and depressing the accelerator pedal, the vehicle failed to exceed 30 MPH. The contact stated that the vehicle was making an abnormal ‘roaring’ sound. The contact stopped the vehicle and had the vehicle to be towed to the dealer. The dealer diagnosed the vehicle and determined that the valve body on the transmission needed to be replaced; however, the part to complete the repair was on a national back order. The vehicle was not repaired. The manufacturer was informed of the failure. The contact stated that the failure was the second transmission failure. The contact had the transmission replaced in 2024 by the same dealer. The failure mileage was approximately 84,000.