(!!!!) (Best Pair) 5R4GYB RCA NOS 1965 same date codes (50-54/40 and 50-55/40 x 2 tubes)
$ 59.99
1 pair) 5R4GYB RCA NOS (6539=1965) same date codes
1 tube) 50/40 and 54/40
1 tube) 52/40 and 54/40
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