5691 RCA Red Base Black Plates used 1948 (2.2/2.4ma) (Gm=62% and 75%)
6B7 Raytheon NOS 1950 era (2 in stock)
6B7 RCA Emerson NOS 1940's
6B7 Sylvania engraved base tests like new 1930's
6D6 Sylvania NOS small 1/8" glass chip inside tube at bottom
6SQ7GT FM Co. by Sylvania used/good 1949 (0.9ma and Gm=800)
6V6GT GE Delco used/good crack in base 1952 (36ma)
