Harley, Harley Davidson, Chopper, 1936 Knucklehead, 1937 Knucklehead, 1938 Knucklehead, 1939 Knucklehead, 1940 Knucklehead, 1941 Knucklehead, 1942 Knucklehead, 1943 Knucklehead, 1944 Knucklehead, 1945 Knucklehead, 1946 Knucklehead, 1947 Knucklehead, panhead, shovelhead