The 7586 is a Nuvistor triode tube. It is used in the 1A1, 1A2, 1A5, M, 321, 3A74, 6R1A, 3A1, 3A3, 4S1, and 3S76. The related 8393 (13-volt version of the 7586) is used in the 1A7 and 453.