The Allison Transmission X-200-4A and X200-4B automatic transmissions are installed in the United Defense M113 family of tracked combat vehicles, powered by 2,800 rpm full load governed diesel engines.

They are other members of Allison's X-series of tracked vehicle transmission products that include the X1100-3B (M1/M1A1/M1A2 MBT), X1100-5 (Razorback AVLB) and X300 (UK Alvis Vehicles Warrior and Hagglund Vehicle CV90 family). The X200-4 Transmission first entered production in 1986 for the M730A2 Chaparral surface-to-air missile carrier powered by the 275 ghp Detroit Diesel 6v-53T Engine.

In mid-1992, the X-200-4A was introduced as a growth version of the original product. It could be used at input levels of up to 350 ghp (298 kW) in vehicles weighing up to 18,144 kg.

In mid-1999 the X200-4B was introduced as a further growth version of the X200-4A. The X200-4B can be used as input power levels of up to 400 ghp (261 kW) with 2,800 rpm full load governed engines.

The highly reliable, successful, X200-4A and X200-4B transmissions of the M113 Family Of Vehicles (FOV) are advanced crossdrive transmissions of the hydrokinetic type. They include a torque converter with automatic lockup clutch for smooth, efficient turning and vehicle control and internally-mounted brake packs for controlled, full-effort stops.