T 55 came in 1959 and it was a development of T 54. The tank had abc-protection and diving ability to the depth of 4 metres. It came in many versions and was the backbone of the tank weapon of the Warshaw Pact into the late 1980s. T 54 and T 55 were very alike looking and had a significant identification mark: a big gap between the to first two wheels. T 55 was produced in tens of thousands into the 1980s. It was exported and is still in duty in various places around the World. In Red China it's called T 59.