About the U.S. M3 Tank:

The M3 light tank was equipped with four VVSS bogies, two per side, a front mounted sprocket and a rear, trailing idler wheel. The trailing increased ground pressure, thus permitting a modest armour increase. Frontal armour was 38mm, while side armor was 25mm. This was by no means adequate, but it was all the chassis could handle. Armament consisted of a bow mounted .30, two sponson mounted .30 MGs, a 37mm M5 main gun with a coaxial .30 MG, and a .30 MG on an anti-aircraft mounting at the turret side.

Unfortunately, the M3 was an outdated design by European terms from the start. The lessons from the Spanish war were interpreted differently in Europe. This resulted in vehicles like the French Char B1, the German PzKpfw III and IV, and the Russian T34. These all had far better protection and armament than the M3.

Stuart Versions:

There were several versions of the M3 light tanks. First, there were four types of turrets. The initial turret was the D37182 turret. This was a slab-sided, hexagonal turret. It used riveted construction and had an octagonal cupola with vision slits. It was found that dedicated MG fire against the turret caused the rivets to break and fly around in the turret. So the same turret design was taken and welded together. This became the D38976 turret. This turret is available in the Academy M3 ‘Honey’ kit.

A third turret type, known as the D39273, was introduced in November 1941, and was easily distinguished from the earlier turrets by its rounded, horseshoe shape and a commander cupola. The initial design called for a rotating periscope but this was not fitted. Vision slits around the cupola provided limited vision. This turret is provided in the Tamiya M3 kit.

The fourth turret type, D58101, resembled the D39273 though without the cupola, and was introduced in early 1942. It had two roof hatches and a pericopic sight for the commander. This turret is in the Academy ‘M3A1’ kit.

The M3 was initially powered by the Continental W-670 radial engine. However, this engine was also needed for aircraft, so other power sources were sought. In September 1940, the use of the Guiberson T-1020 diesel engine was authorized. This engine had a slightly different engine deck layout, with the pipes for the air filters running into the engine grill, instead of entering the hull near the air filters. Tamiya provides the Guiberson layout on their tank. The diesel engined vehicles were not popular in the army, because of reliability and the logistic problems of operating gasoline and diesel powered vehicles together. The Marines had less problems, as diesel fuel was already used for their landing craft.