6EU7 GE NOS 1960's (48/32 and 56/32)
7591 Fisher Westinghouse used/good/75% 1963 (43.5ma, Gm=7450)
7591 Tungsol used good 1963 (55ma, Gm=8100)
7591 Westinghouse branded RCA NOS 1963 (51.5ma, Gm=9050)
7591A Sylvania branded RCA coin-base NOS 1970's (63ma, Gm=10,000)
7591A Sylvania branded RCA used/75% 1968 (51ma, Gm=7,600)