(!!!) 6S4A RCA black plate NOS 1960's faded printing (20ma)
(!!) (Best Pair) 6S4A Westinghouse NOS black plates same date codes 1963 (22.2ma and 22.5ma)
(!!) (Best Pair) 6S4A Westinghouse NOS black plates same date codes 1963 (23.5ma and 24.2ma)
6S4A GE Admiral NOS 1965 (27.5ma)
6S4A GE NOS 1962 (25ma)
6S4A Raytheon NOS 1961 (20ma)
6S4A RCA USA black plate NOS 1960's (23ma)
