(!!!!!) (INFORMATION) 6N1 or 6N1P (Best Sounding Substitutes = 6BK7B, 6BQ7A, 6BZ7)
(!!!!) (Best GE Single 1957) 6BK7A GE gray plates NOS "U" getter 1957 (9.8/10.8ma)
(!!!!) (Best GE Single) 6BK7B GE gray plates NOS "U" getter 1974 (8.0/8.8ma)
(!!!!) (Single) 6BK7B GE gray plates NOS "U" getter 1963 (6.2/5.4ma)
(!!!!) (Single) 6BK7B RCA NOS "U" getter 1950's (7.5/8.5ma)
(!!!!) (Single) 6BK7B Tungsol branded RCA "U" getter 1957 (10/14ma)
(!) (SINGLE) 6BZ7=6BQ7A GE GM Delco "U" getter NOS 1950's (11.6/10ma)
