(!!) (Best Single) 7N7 Sylvania branded Philco NOS parallel black plates 1940's (7.5/7.9ma)
(!!) 7N7 Sylvania branded Philco used/good short bottle parallel gray plates 1948 (7.2/7.6ma)
(!) (Best Single) 7N7 Sylvania NOS 1960 era (10.8/11.2ma)
(!) (Good Single) 7N7 Sylvania branded GE NOS 1961-1962 (7.5/8.3ma)
(!) (Recommended Single) 6L6GC Sylvania NOS 1960's (63.5ma)
6L6GC Sylvania clear top NOS 1960's copper grid posts (68ma)