It's now November 1942 and it still shows no way to upgrade the ship itself. Yes, I see to upgrade RADAR, AA guns, and the deck guns, but not the conning tower. I haven't been offered an option for it...I'm still confused.
I got some pictures if you're having trouble understanding. How do I turn a sub with this conning tower...
Into a sub with THIS conning tower...?
Do I actually need to buy the sub in that year to get this version? If so, I think this is quite unrealistic because in real life subs would be ripped apart and put back together again with totally different looks.