[Arran]

No, the Pentagon with СССР and some lines inside is the Soviet "Quality Mark", was put on the consumer goods, not military.
The military, such as the tube I wrote about on eBay, have a diamond with some number inside.

Mike;
  I see the diamond mark, and it also has an "OTK" mark next to it. Personally I think that seller's prices are rather high, mil spec or not, Soviet/Russian EL84s are all over the place, and still being made, also Western made NOS EL84s are also not too hard to find.
  Given my experience with EL84s I would not want to build a home made amp using them, and I think that anyone wanting to manufacture new amps using the same is crazy. Whilst they do work they also run extremely hot since a 6BQ5/EL84 is basically a 6V6GT stuffed into a mini nine pin envelope, and the way some newer audio amps are designed they drive them to the limit which further shortens their life. In the case of this Fisher TA-600, it's a restoration so I would use whatever the factory used, unlike some of the companies building amps today they probably operated the tubes withing recommended specs anyhow. However if I were to build a home brew amp I would use 6V6GTs, or possibly 6K6GTs, both were used as vertical output amplifiers in B&W TVs back in the 1950s, same with 25L6GTs, so there are more good used and NOS ones around then anyone could ever use.
Regards
Arran