(!) Recommended Pair) 37 RCA branded GE NOS 1946 and RCA like new 1930's (7.3ma and 8.3ma)1 pair) 37 RCA branded GE NOS 1946 and RCA like new 1930's 1 tube) 7. 3ma Gm=1100 RCA branded GE NOS 1946 NOS 1 tube) 8. 3ma Gm=1100 RCA Cunningham engraved abse 1930's like new Test parameters: Vplate=250V Vgrid= 18V Iplate good range 6. 5 8ma Gm=1000 1100 (Filament=6. 3V @ 300ma, many think the 37 sounds better than the 76)