Specification Crew : 4 Engine : Continental Radial 250hp Combat weight :12,523 kg (27.552 lb) Max speed : road 56 km/h (35 mph) Range : 112 km (70 miles) Length : 3.29 m (14.8 ft) Width : 2.24 M (7.34 ft) Height : 2.51 m (8.25 ft) Main gun : 37mm

Developed from the M2A4 the M3A1 incorporated improvements found to be necessary from experience with the earlier vehicle.The main change was the introduction of a large trailing idler wheel in place of the idler of the M2A4.This refinement helped to improve stability.As the M3A1 Stuart came after the outbreak of war it was able to benefit from information gleaned from combat experience. Armament remained the same as M2A4 but it had ticker armour on the front plate and reinforced suspension to take the greater weight.Its hull was welded rather then riveted and from mid-1941 a gyro-stabilization system was introduced for the main gun , while external fuel tanks were added for additional range.The M3 entered production in March 1941 and some of the first production models were in the hands of British tank units in the Middle East by August of the same year.The M3 was called the Stuart I by the British War Office and was classed as a light cruiser tank by virtue of its armament and armour.The armament of the M3A1 consisted of a 37mm gun and three 0.3in Brownings , one coaxial with the main gun , one in the hull front and one as an antiaircraft gun on the turret roof.A variant of the M3 was the T2 mine exploder.