WE 421a - Black Plates from 1967 | WE 5998/421a - Grey Plates from 1954 | Chatham 5998 from 1960 | Tung-Sol 5998 from 1966 | What's Best Audio and Video Forum. The Best High End Audio Forum on the planet!
The 5998 Tube
SOLD: FS: Tung Sol 5998 Domino plate Tube | Stereo, Home Cinema, Headphones Components
Visual evidence Tung-Sol 5998 = Western Electric 421 | Headphone Reviews and Discussion - Head-Fi.org