A rear drive module for a drive train assembly for transferring torque to front wheels and rear wheels of an all-wheel drive motor vehicle comprising: a differential assembly having an outer differential housing and an inner differential housing, the inner differential housing being fixed for rotation with an output shaft of the differential assembly; a ring gear assembly having a ring gear mounted to and fixed for rotation with the outer differential housing; and a disconnect and synch-lock mechanism operable to synchronize and lock the inner differential housing and the outer differential housing, and to disconnect the inner differential housing and the outer differential housing such as when torque is not being provided from a front driveline of the vehicle for driving the rear wheels in order to prevent rotation of the outer differential housing and the ring gear and churning and parasitic bearing losses associated therewith, the disconnect and synch-lock mechanism comprising a synchronizer clutch and a clutch actuator, wherein the synchronizer clutch comprises a multi-plate clutch having a drum fixed for rotation with the outer differential housing, a first set of plates connected to the drum, and a second set of plates connected to the inner differential housing; the clutch actuator is operable to generate an axial force in a first direction towards the differential assembly to activate the synchronizer clutch and the clutch actuator comprises a ball ramp mechanism; and the ball ramp mechanism comprises a first cam plate defining a first groove, a second cam plate defining a second groove facing the first groove, and at least one actuator ball disposed between the first cam plate and the second cam plate in the first and second grooves, wherein relative rotation of the first and second cam plates (96, 98) causes axial translation of the second cam plate in the first direction for axial movement of an adjacent apply plate to activate the synchronizer clutch, characterized in that the apply plate comprises a spring and a ball, and a first surface of the second cam plate defining one or more detents for engaging the ball of the apply plate. a differential assembly having an outer differential housing and an inner differential housing, the inner differential housing being fixed for rotation with an output shaft of the differential assembly; a ring gear assembly having a ring gear mounted to and fixed for rotation with the outer differential housing; and a disconnect and synch-lock mechanism operable to synchronize and lock the inner differential housing and the outer differential housing, and to disconnect the inner differential housing and the outer differential housing such as when torque is not being provided from a front driveline of the vehicle for driving the rear wheels in order to prevent rotation of the outer differential housing and the ring gear and churning and parasitic bearing losses associated therewith, the disconnect and synch-lock mechanism comprising a synchronizer clutch and a clutch actuator, wherein the synchronizer clutch comprises a multi-plate clutch having a drum fixed for rotation with the outer differential housing, a first set of plates connected to the drum, and a second set of plates connected to the inner differential housing; the clutch actuator is operable to generate an axial force in a first direction towards the differential assembly to activate the synchronizer clutch and the clutch actuator comprises a ball ramp mechanism; and the ball ramp mechanism comprises a first cam plate defining a first groove, a second cam plate defining a second groove facing the first groove, and at least one actuator ball disposed between the first cam plate and the second cam plate in the first and second grooves, wherein relative rotation of the first and second cam plates (96, 98) causes axial translation of the second cam plate in the first direction for axial movement of an adjacent apply plate to activate the synchronizer clutch, characterized in that the apply plate comprises a spring and a ball, and a first surface of the second cam plate defining one or more detents for engaging the ball of the apply plate.