The contact owns a 2018 Ford F-150. The contact stated that while driving at an undisclosed speed, an abnormal sound was coming from the transmission while upshifting from the 5th gear to the 8th gear. No warning light was illuminated. The vehicle was taken to the dealer and was diagnosed with transmission failure. The vehicle was repaired; however, the failure reoccurred. The vehicle was diagnosed, and the contact was informed that the transmission needed to be replaced. The manufacturer was made aware of the failure but offered no assistance since the vehicle was not under warranty. The approximate failure mileage was 49,000.