Because a 2x2 transmission is not designed to handle the additional power and torque required for four-wheel drive, it cannot be used on a 4x4 truck. It would not be able to adequately transmit power to all four wheels, resulting in poor performance and potential damage to the transmission and other components of the vehicle.
Therefore, it is not recommended to use a 2x2 transmission on a 4x4 truck. It is essential to use the correct transmission that is compatible with the vehicle's drivetrain configuration to ensure proper operation and longevity of the vehicle.