And what do you mean by queue locked up for unifying the source codes? How does that affect the games development and why did they do it. And earlier you were saying that they were adding new subs. Are they not doing that anymore?

Anyway, doing a bit more research I noticed that there were many other submarine classes between the V boats and the Gato class. As far as I can tell, all the subs in the US navy tree are o boats, s boats, and V-boats with the exception of the Gato. It would probably be better to replace some of them with the boats that are more modern than the O-Boats, but less so than the Gato. These classes were the Porpoise class, Salmon Class, Sargo class, and Tambor class. I wouldn't use all of these boats, because many of them are similar to the Gato, but perhaps get rid of the O class and make the S class the SS1, the O saw little or no action, it was only used for training. The S class actually saw combat and though not great as a whole class, some of the S boats did well. The only V boats that were active during WW2 as combat ships were the Narwhal type boats, the Dolphin, and the Cachalot class. The Barracudas never saw any action, and Argonaut was not made for combat in the traditional sense (was a mine layer and then troop transport, it was sunk without ever launching a single near successful attack). The less modern S type performed better than most of the V boats, the exception being Narwhal and the Cachalot class (though in terms of actual combat, the S-boats did better than the cachalots even.) So here is the list, S-Boat, Cachalot, Narwhal, (Dolphin or some boat after Dolphin but before the Gato, perhaps the Sargo class since the Sargo had the distinction of sinking the first Japanese ship to be sunk by US forces on entry into WW2) Gato, and Balao in that order for the revised American sub tree.