http://bama.edebris.com/manuals/eico/666/
tube 27..2.5V..7..66..23511..11111..4..3..leak 2,3,4with line under..merit 2
tube171A..5.0V..7..38..23511..11111..4..2..leak 2,3..merit 2
tube 80..plate 1..5.0V..0..61..21411..11111..4..1..leak 2,3..merit 3
tube 80..plate 2..5.0V..0..61..24111..11111..4..1..leak none..merit 2
hope this helps,
Tom