The M3 Tank

Standardized July 1940, this was the replacement for the outdated M2 series. This tank series would achieve lasting fame known as the "Stuart". The British who bought many prior to and after the United States entering the war gave this name to the tank. Further sub designators by the British were Stuart Mk 1 and Stuart Mk 2. The Mk 1 was gasoline powered and the Mk 2 was diesel powered. Soldiers of the United States had no special affectionate name for this vehicle (though they probably had a few un-affectionate names). This tank was built a bit on the heavy side of light tanks of the period as it came complete with a 37mm main gun and five .30cal machine guns (what other "light" tank can claim that). It was also noted for having stronger and heavier armor than it's foreign sisters (10 - 44mm).

Fast and reliable, the only downside of this vehicle was that the crew compartment was designed a bit on the clumsy side. Test variations were numbered M3E1, M3E2, M3E3 and mostly centered around diesel versus gasoline engines. No diesel tanks were adopted for US Army use. The M3E2 was a twin Cadillac V8 engine combination driven through twin automatic transmissions. The Ordnance Department expressed doubt in the design and so GM had the tank driven from Detroit all the way to Aberdeen under it's own power, achieving 50mph, and with no problems. The M3E2 went on to become the M5. The M3E1 involved a Cummins Diesel and was rated as "satisfactory" but was "not adopted due to diesel policy". That was a reference to a priority the Navy had on all diesel fuel. M3E3 seems to have involved tests with a cast homogenous turret, a sloping front plate, storage box, and an attempt to reduce bullet "splash". All M3 tanks were built by American Car & Foundry. The US M3 Stuart series was the first American tank to see active service in WWII, and did so in North Africa.

Specifications

Crew	4
Weight	27,000 lbs
Length	14' 7"
Width	8' 4"
Height	8' 2 3/8"
Armor	3/8" - 1.5"
Armament	1 x 37mm, 4 x .30cal
Powerplant	See engine chart
Performance	35 mph

Engines

Continental	A 7 cylinder radial air cooled gasoline engine Model W670-9A, 250hp.
Guiberson	A 9 cylinder radial air cooled diesel engine model T1020 Series 4, 250hp.
(M3E1) Cummins	Model HBS 600 Diesel, 6 cylinder. The vehicle weighted 27,300 lbs.
(M3E2) Cadillac	Twin V8 Cadillac engines supplied power @ 150hp each through twin automatic transmissions. The M3E2 weighed 28,165 lbs.

Source : http://bataan.cerbus.net/tank.htm