Harley-Davidson's first flathead V-twin appeared in 1929 as the Model D. Its 45-cubic-inch engine was smaller than the company's existing 61- and 74-cubic-inch F-head V-twins, which then became known as 'Big Twins'. The latter switched to a flathead design the following year, but those larger engines were neither as reliable nor as long-lived as the under-stressed 'Forty-five'. Though the Forty-five was no powerhouse, it proved to be a versatile engine that remained in production for more than four decades. During that time, it served duty not only in street motorcycles, but also in three-wheeled Servi-Cars (1933 -1973), military WLAs of the 1940s, and WR racing bikes of the 1940s and 1950s. This project bike is accompanied by it's custom built travelling crate, as illustrated.