Here are 5 6S4 6S4A electron rectifier amplifier vacuum tubes by assorted makers. I do see a Tung-Sol, a GE and a Delco. They tested on my TV-7 at 82,82,74,68,and 82 with minimum values of 52, so good tubes. They were also tested for shorts.

I purchased a large collection of mostly NOS vacuum tubes which I will be listing so be sure to check my other listings.