I received your PM, V13.
There is a bunch of unused stuff among the stock files. Some are easily put in game (see Rongel's thread about ship cargo), some others are not. An example?
A while back I and Volodya tried getting the twin M42 to work. It worked if manned by AI crew, but we couldn't move the mouse or even walk close to it, or the game freezed. I didn't surrender on this one yet, but right now I am busy with other stuff.
Talking about your request, it is possible that one day we will get working U-flaks but, as far as I am concerned, at this moment I have not fully clear the way conning tower upgrades are set in game. Any contribution on this subject highly appreciated