(!!) (Best Pair) 6CZ5 RCA black plate 1960's same build (49.5ma and 51ma)
6CZ5 GE Canada black plate NOS 1969 (49ma) (Same build as RCA)
6CZ5 GE Europe gray plate NOS 1975 (60ma)
6CZ5 RCA black plate short bottle used/good 1960 era (48ma)
