For clarity: I purchased this tube directly from the manufacturer of my head amp probably ~20 years ago. I have no reason to believe that this tube was not sold under the Bendix label.
Commonly big tube manufacturers like RCA sold their tubes under other labels. Often the final seller like Bendix would do their own testing and then sell the tube for more demanding applications requiring low noise, low microphonics or extended life. This tube seems to have been made for aviation. Held to a higher standard, often the industrial version of tubes work better for audio. Bendix also made their own tubes.
Those interested in actually purchasing should feel free to contact me offline with any questions or comments.
If your comments are useful and informed I will amend my ad.
Thanks.