The T-70 was an attempt to remedy some of the shortcomings of the T-60 scout tank, which had very poor cross-country mobility, thin armour, and an inadequate 20-mm gun.

It also replaced the very short production run of the T-50 light infantry tank, which was more sophisticated, but also much more complicated and expensive to produce.

It was quickly redesigned as the T-70M (although it continued to be referred to as just T-70), with the engines in-line on the right side of the tank and a normal transmission and differential.

The conical turret was replaced by one more easily welded out of plate armour, and moved to the left side of the hull.

Curiously, even after the T-70's production line was redesigned, SU-76 self-propelled guns started to be built with the same unsatisfactory unsynchronized two-engine layout, and all of them were later recalled for factory rebuilding as SU-76Ms.

The end of the T-70's production run was built with two 85-hp GAZ-203 engines, a Mark 4 commander's periscope replacing a vision slit, and other improvements.

The Soviets did start development work on an amphibious light tank in 1945, resulting in the post-war PT-76, introduced in 1954.