(!!!) (Recommended Pair) 5881 Tungsol branded RCA and Tungsol used/very good 1950's - 1960 (70ma and 66ma)
(!!!) (Recommended Single) 5881 Tungsol NOS 1950's branded 6L6GB (86ma)
(!!!) (Recommended Single) 5881 Tungsol rebranded Sylvania 1960 era (77.5ma)
(!) (SINGLE) 6BQ5=EL84 Heath Mullard Great Britain used/good 1959 (40ma)