This icon was a supertest leak.
The in-game description was also leaked: At the end of World War II, consideration was given to a redesigned and upgraded M4 Sherman. A larger and stronger turret ring would have allowed mounting of the M26 turret and a 90-mm gun. However, the M26 was chosen for mass production.
There is not much about this tank; its a M4A3E4 sherman with a M26 pershing's turret.