Harley-Davidson models. In the late summer of 1929, Harley-Davidson introduced its 45 cubic inches (737 cm³) flathead V-Twin to compete with the Indian 101 Scout and the Excelsior Super X. This was the "D" model, produced from 1929 to 1931. Riders of Indian motorcycles derisively referred to this model as the "three cylinder Harley" because the generator was upright and parallel to the front cylinder. The Great Depression began a few months after the introduction of their 45 cubic inch (737 cm³) model. Harley-Davidson's sales fell from 21,000 in 1929 to 3,703 in 1933. Despite this, Harley-Davidson unveiled a new lineup
Harley-Davidson and for private buyers. Harley-Davidson, on the eve of World War II, was already supplying the Army with a military-specific version of its 45 cubic inches (740 cm³) WL line, called the WLA. The A in this case stood for "Army". Upon the outbreak of war, the company, along with most other manufacturing enterprises, shifted to war work. More than 90,000 military motorcycles, mostly WLAs and WLCs (the Canadian version) were produced, many to be provided to allies. Harley-Davidson received two Army-Navy ‘E’ Awards, one in 1943 and the other in 1945, which were awarded for Excellence in Production. Shipments