The truck will spontaneously downshift when driving. This creates a intense bang and vibration in the vehicle with an instantaneous speed change of vehicle. It’s quite scary when it happens. I don’t believe that it’s any good for the drive shaft or rear end with such a sudden instantaneous transmission shift. I fear for additional damage it to the vehicle and the existing drivetrain when this occurs and could cause an accident if someone is following too close to the back of me when this happens.