[Milsurplus] Oddball (to me) antenna connector?

[KD7JYK DM09]

Every now and then, I come across a piece of equipment with the 
connector shown on the antenna at this link:

https://aeroantique.com/products/antenna-as-114-for-countermeasure-radar-an-apt-4-wwii-b-29-b-24?variant=32451588042

It looks like a fat N-connector, with an SO-239 receptacle pin in the 
center, BUT, it's 3/4"-26 (or 27, NOT 28).

I've seen a few on pics of WWII counter-measures equipment, and some radar.

Some items do not lend themselves to modification, so, I'm hoping to ID 
the exact connector type, and I'll go from there.  I'm sure a few people 
will know right off, but the web sure doesn't...

Ideas?

Thanks.

Kurt