(!!) (slightly microphonic pair) JAN-6SL7GT=VT-229 RCA NOS and like new 1940's (2.5/2.4ma and 2.4/2.6ma) 1-3% matched
(!) 6SL7GT RCA burgundy base NOS 1951 (1.7/1.8ma)
6C8G CBS NOS 1950's (like RCA) (3.7/4.1ma)
6C8G National Union NOS 1950 era (3.6/5.8ma)