Also known as: M6重戦車, M6A1, M6A2E1
In response to World War II breaking out across the Atlantic, the US decided to develop a new 50-ton heavy tank for their army, designated as T1. The design utilized a turret that held two cannons, a 3-inch tank gun and a 37 mm gun mounted side-by-side. Further development on the type of transmission to use with the heavy tank culminated with the T1E2 cast construction variant that utilized a torque converter transmission design was selected for standardization as the M6 heavy tank, with a second variant T1E3 with the same transmission that was constructed by welding was selected as the M6A1*. A total of 40 tanks from the M6 family were assembled, 12 of which were the M6A1 variant. However, by the time these heavy tanks were ready for mass production, the U.S. Army had lost interest in them, considering the M4 Sherman as a better solution in terms of reliability and cost-effectiveness