[Milsurplus] Some odd tubes - what are they?

[Kenneth G. Gordon]

I was out to an SK's shack today with his son and daughter looking over what 
is left there.

In a box which contained 6 other identical boxes we found 6 tubes, NIB, 
which are labled on the outside 10E 7.5 - 36 VT-25.

>From a look inside the glass, it is obvious that they are triodes. The plates 
are fairly tall and there is a significant gap between the plate and the grid.

The bases are not like anything I have ever seen though. They are a 
brown-bakelite like material with is almost 2" square with what looks like a 
silver-plated banana plug at each corner, one (or two) a bit larger in diameter 
than the others.

The glass doesn't look quite like an ST shape either.

I thought at first they were simply 10Ys or VT-25As, but now I don't think so.

Looking for a 10E I find some european pentode online, which looks 
considerably different from this one.

Anyone have any idea what this is, and how much it might be worth? The 
owners would like to sell them, along with a bunch of other stuff.

Ken W7EKB