The design bureau of A. A. Morosov developed a replacement for the T-34.2 Originally it was designed to have the 100 mm D-10 T tank gun, however, it was too large for the T-34/85 turret.2 It was then decided to install an 85 mm gun.2
The engine was installed traversely and this resulted in the length of the hull to be shorter and this in turn saved weight.2
Entered production in 1945. Few models were built and most saw teething problems due to rushed development. Some of the later models had 100 mm guns installed.