senior Nash models used identical bodies, relying on a longer wheelbase as well as the hood and front fenders (plus subtle trim augmentations) to provide visual cues to differentiate the more expensive Eights from the less expensive Six models. Beginning in 1937, even the low-priced LaFayette series came under this plan. This basic formula was used through the final AMC Ambassador in 1974, with the exception of 1962 to 1964, when the Rambler Ambassador and the Rambler Classic shared the same wheelbase and front sheet metal. In 1937, Sinclair Oil Corporation teamed up with Babe Ruth in a baseball contest where a 1937 Nash Ambassador Eight sedan was awarded every week. A custom-designed and specialty-built convertible model was marketed for 1940, the Sakhnoffsky Special Cabriolet. For the 1941 and 1942 model years only all Nash vehicles became Ambassadors and rode both long and short wheelbases. The Ambassador Eight now shared the Ambassador Six's . The Nash Ambassador 600, built on a wheelbase, became the first popular domestic automobile to be built using the single-welded "unibody" type of monocoque construction that Nash called "Unitized", rather than body-on-frame. From 1941 through 1948, Nash Ambassador models placed this unibody structure on top of a conventional frame, thus creating a solid and sturdy automobile. It was also one of the first cars in the "low-priced" market segment with coil spring suspension in front and back, giving it "the Arrow-Flight ride" along with other benefits. In the spirit of wartime conservation, the Ambassador Six and Eight lost their twin ignition feature for 1942, reverting to a single spark plug per cylinder. The 1941-42 Ambassador 600 was also the only Ambassador ever powered by an L-head engine. Nash would remain with this model arrangement through the post-war 1946-1948 model years, although the 600 would no longer be known as an Ambassador. Civilian car and truck production was curtailed during World War II (1942-1945) and companies turned to production that became part of the "arsenal of democracy." 1946-1948 When production was resumed after the war, the Eights were no longer part of the program. The 1946 Ambassador Six was now the top of the Nash line. In 1946 Nash introduced a wood-paneled version of the Ambassador called the "Suburban". Featuring high-quality ash framing, with mahogany paneling supplied by Mitchell-Bentley of Owosso, Michigan, the Suburban coachwork was based on the handsome “slipstream” sedan, a classic 1940s streamlined design.