Stuart Tank Vol. 2: The M5, M5A1, and Howitzer Motor Carriage M8 Versions in World War II. The Stuart light tanks were the first tanks taken into combat by US troops during WWII. Production of these vehicles can be broken into two categories: the early tanks powered by air-cooled radial engines, and late vehicles powered by twin V-8 engines. This volume explores the late vehicles with Cadillac water-cooled engines, the M5 and M5A1, as well as the M8 Howitzer Motor Carriage. 9" x 9" x .65".