(!!!!) (Best 5691 Single) 5691 RCA Red Base NOS 1950's rebranded WL-5691 Westinghouse 1960 (2.2/2.3ma) 1-2% section balance
(!!) (Recommended Single) 5691 RCA red base gray plates NOS 1975 (2.4ma/2.9ma)
5691 RCA Red Base gray plates low hours/tests like new 1966 - broken center guide pin (3.1/3.2ma)
