(1) Tested GE 6CU5 & Box Date Code CZ Gray Plate General Electric Power Pentode

(1) Tested Very Strong GE 6CU5 & Box Date Code NF Gray Plate Power Pentode (a)

(1) Tested Very Strong GE 6CU5 with Box Date Code EL Gray Plate Power Pentode

(1) Tested Strong GE 6CU5 with Box Date Code MK Gray Plate Power Pentode Tube

(1) Tested GE 6CU5 & Box Date Code NF Gray Plate Power Pentode (b)

(1) Tested GE 6CU5 with Box Date Code LW General Electric Power Pentode Tube

(1) Tested Very Strong GE 6CU5 with Box Date Code FJ Gray Plate Power Pentode

(1) Tested Sylvania 6CU5 with Box Date Code DED hh Black Plate Power Pentode