The ZSU 23-4 (known as 'Shilka') from 1960 this was an awesome development in AA defence within the Warsaw Pact, and indeed still today is both excellent for close air and ground support.
Armed with four 23mm autocannons and radar guided, the chassis provided by the PT76 it caused NATO a major headache and continues to do so, though supersceded by various missile systems. THis weapons system has seen action in ward such as the om Kippur War, Vietnam, Gulf Wars 1 & 2 and is till involved in the war in Ukraine. Over 6500 have been producedand is still in production.