An integrated system for automatically controlling the operation of both an automated mechanical transmission and a multiple speed axle assembly in a vehicle drive train assembly includes a transmission actuator for operating the transmission in any one of a plurality of transmission gear ratios. The system further includes an axle actuator for operating the axle assembly in any one of a plurality of axle gear ratios. An electronic controller is provided for operating the transmission in a desired one of the plurality of transmission gear ratios and for operating the axle assembly in a desired one of the plurality of axle gear ratios to provide a desired overall gear ratio for the vehicle. To accomplish this, the electronic controller is responsive to one or more input signals that represent operating parameters of the vehicle. When it is determined that a change in the overall gear ratio of the vehicle is necessary, the electronic controller operates one or both of the transmission actuator and the axle actuator to achieve the desired overall gear ratio. The determination of whether the transmission actuator alone is actuated, the axle actuator alone is actuated, or both the transmission actuator and the axle actuator are actuated will depend upon the specific gear ratios provided by the transmission and the axle actuator, the current overall gear ratio, the desired overall gear ratio, and other factors.