TM 9-2320-361-20 1-10. EQUIPMENT CHARACTERISTICS, CAPABILITIES, AND FEATURES (Contd) e. M50A2, M50A3 Water Tank Truck, WO/W and W/W. PURPOSE: M50A2 and M50A3 water tank trucks are used to transport and discharge water. Filling, emptying, and transferring water is done the same way fuel is filled, emptied, and transferred on the M49A2C fuel tank truck. The M50A2 has a 400-gallon (1514 L) tank in front and a 600-gallon (2271 L) tank located over the rear axles. The M50A3 has two 500-gallon (1893 L) tanks. Only the tank located over the rear axle may be filled for cross-country operations. M50A2, M50A3 WATER TANK TRUCK W/W f. M109A3 Shop Van Truck, WO/W and W/W. PURPOSE: M109A3 shop van truck is used as a mobile repair shop. It may be used to transport special equipment that must be kept free of dirt, dust, and moisture. This vehicle is not reducible in height. M109A3 SHOP VAN TRUCK W/W 1-6