would ultimately become the M4 Sherman. However, until the Sherman was in production, an interim design with a 75 mm gun was urgently needed, and this is where the M3 came in. The M3's design was somewhat unusual as the main weapon, a larger caliber, low-velocity 75 mm gun, was mounted in an offset sponson within the hull, giving the gun a limited traverse. A small turret with a lighter, high-velocity 37 mm gun sat on the tall hull. An even smaller cupola on top of the turret held a Browning M1919. The British ordered the M3 when they were refused permission to have their own tank designs (the Matilda infantry tank and Crusader cruiser tank) made by American factories. British experts had viewed the mock-up in 1940 and identified several flaws — the high profile, the hull mounted gun, radio in the hull, smooth tracks, the amount of armor with insufficient attention to splash-proofing the joints. The British agreed to order 1,250 M3s, to be modified to their requirements - the order was subsequently increased with the expectation that when a superior tank was available it could replace part of the order. Contracts were arranged with three U.S. companies, and the total cost was approximately US$240 million. This sum was all of the British funds in the US and it took the Lend-Lease Act to solve the financial problems. The prototype was completed in March 1941 and production models followed with the first British specification tanks in July. The British cast turret included a bustle at the back for the Wireless Set No. 19 radio. It had thicker armour than the U.S. one and removed the U.S. cupola for a simple hatch. Both U.S. and British tanks had thicker armor than first planned. The British design required one fewer crew member than the US version due to the radio in the turret. The U.S. eventually eliminated the full-time radio operator, assigning the task to the driver. After extensive losses in Africa and Greece, the British realized that to meet their needs for tanks, both the Lee and the Grant types would need to be accepted. The U.S. military utilized the "M" (Model) letter to designate nearly all of their equipment. When the British Army received their new M3 medium tanks from the US, confusion immediately set in, as the M3 medium tank and the M3 light tank were identically