The Y Type was in high demand by British forces during the First World War, in 1917 AEC installed a moving assembly line to make the type, enabling the factory to produce 130 chassis per week. In addition to British forces the type was also used by the United States Army in France. By armistice in 1918, AEC had built 8,821 Y Types, 5200 of which were fitted with the Tylor engine.