Not saying it would be a simple task, but it could be modded.
There's already a mod that has changed some of the big guns on the Jap warships from one type to another.
If the conning tower and sub body are one piece models and cannot be seperated, it would have to be altered in 3Dsmax. But, several versions of the same class of boat could be made with different conning towers, and swapped during the game in port.
Not sure of the exact method of swapping as I've only thought about this for 30 seconds now, but I bet it can be done.
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