(!!!) (Recommended Pair) 7591A GE coin-base NOS original boxes 1981 (79ma and 83ma)
7591 Tungsol used good 1963 (55ma, Gm=8100)
7591A Sylvania branded RCA coin-base NOS 1970's (63ma, Gm=10,000)
7591A Sylvania branded RCA used/75% 1968 (51ma, Gm=7,600)
