[Milsurplus] Mounting Aircraft Antennas?

[KD7JYK DM09]

I have recently acquired the following antennas:

https://www.ebay.com/itm/Transponder-Antenna-AT-184-AP-AF-8351-Phaostron-Co-/283143629873

And:

https://www.ebay.com/itm/Phaostron-AT-185-AP-Antenna-AF8351-/373205080085

I found the "white bronze" alloy used for the connectors interesting, 
although they have the stink of silver, but, my question is, how the 
heck were they mounted????

I found a drawing online showing a craft with such antenna on it, 
mounted flush to the fuselage, but as you can see, there really isn't 
any way to do this.  The nut on the bottom of each antenna connects to a 
long rod passing through the antennas that pulls the three parts, top 
element, insulator, and bottom element, together.  There is a rubber 
gasket on the bottom of each antenna to seal between the body of the 
antenna, and the surface of a craft.  The nut is split, and crimped in, 
probably a sort of lock-nut.  Aside from that, there are odd notches in 
the sides of each antenna.  These recesses are machined into the 
aluminum lower portion, and there is a dull gray metal plug in each one. 
  There is no corrosion, or oxidation, but each plug holds a magnet very 
well.  I had a heck of a time getting a small "super" magnet off of one, 
and the plug was quickly magnetized in itself.  The lower portion of 
each antenna, aside from a small hole for the rod that holds them 
together, and a small passage for the center pin of the RF connector, 
from bottom, to top, is solid aluminum.

Any ideas on how these would have been mounted to an aircraft?  I just 
can't figure it out...

Thanks.

Kurt