The Allison Transmission Division X4560 Powertrain is a major subsystem of the US Marine Corps Advanced Amphibious Assault Vehicle (AAAV) currently under development by General Dynamics Amphibious Systems.

It consists of four major components: Transmission and Power Transfer Module (PTM) and Final Drive and Automatic Drive Shaft (ADS). The Powertrain provides transmission range control, vehicle steering, vehicle braking, Power Take-Offs (PTOs) and a unique power management system. This splits power between the water jets and tracks, and manages the land, sea and transition modes of vehicle operation.

The remotely mounted transmission houses an oil-cooled brake system based on the Allison X300 Transmission used in the British Warrior and Swedish CV90 family of tracked combat vehicles.

The transmission electronic controls and six-speed planetary-type range pack are common with Allison's popular commercial World Transmission. The Hydrostatic Steer Unit (HSU) is a 22 in3 version of the reliable X1100-3B installed in the MIAbrams MBT RVC35 HSU. The PTM houses the torque converter and water jet drive train.

The torque converter provides an automatic lockup clutch for improved fuel economy and evacuates during idle conditions to reduce engine load. The PTM also houses the water jet clutch and drive train used to transfer power to the water jet drive shafts.

The AAAV final drives provide transmission mounting, speed reduction and include a quick disconnect mechanism allowing disconnection of the final drives from the transmission outputs in under 5 minutes.

The first set of prototype hardware was delivered to General Dynamics Amphibious Systems March 1999.

Prototypes. Not yet in production or service.