I'd have to say the E Model and the Mack Jr. were the best of the late 30's...here is some info from Mack's History website: 1936 The name of the International Motor Company is changed to the Mack Manufacturing Corporation. The Mack E series, introduced in 1936, were streamlined, medium-duty trucks with gross vehicle weight ratings ranging up to 23,000 lbs. The E models were available in both conventional and cab-over-engine configurations and proved themselves among the most versatile products ever offered by Mack. Over 78,000 were produced through 1951. Mack was one of the first truck manufacturers to apply four-wheel brakes to heavy-duty trucks, increasing braking ability and safety, particularly with heavier loads. In 1938, Mack became the first truck manufacturer to design and build its own heavy-duty diesel engines, establishing the tradition of "balanced design" (in which the integration of the powertrain and vehicle design maximize performance) that continues today. Mack was a major military contractor on a much larger scale in World War II, with more specialized products. Mack trucks served the Allied forces 35,000 strong in that second conflict, in the form of prime movers, personnel carriers, wrecker trucks, tank transporters, and more. 1936-1938 Mack merchandised a series of trucks under the name "Mack Jr." The vehicle was actually built by the Reo Truck Company in Lansing, Michigan. The vehicles were built according to Mack specifications and were sold through the Mack sales organization. In total, there were 4,974 chassis built during this time frame. This was the second time in its history that Mack sold a Mack junior chassis. The 1936-1938 units should not be confused with the earlier Mack Junior; production on that version began in 1909.