"Central Committee of the CPSU and the Council of Ministers of the USSR
Decree
May 20th, 1968
On the installation of a more powerful set of armament into the T-64 tank.
The Central Committee of the CPSU and the Council of Ministers of the USSR decree that:
In agreement with the proposal of the Ministry of Defense of the USSR and the Ministry of Defense Industry of installing into the T-64 tank a new 125 mm smoothbore D-81 gun with armour piercing subcaliber, HEAT, and HE-fragmentation shells, two-plane stabilizer 2E23, TPD-2 rangefinder sight, and a PKT coaxial machinegun with main characteristics in accordance to attachment #1.
The T-64 tank with new armament will be called T-64A."