The model is infested with errors. The rivets do not exist on the real boat. Not worth the effort to correct them all, in my opinion . I am extremely disappointed in the model.
Well you have to cut them some slack; it's not as if they had a real Type IX they could examine in detail and model it after.......oh, wait!
Seriously, it is a huge disappointment when in those rare instances for WWII submarines that an actual 1:1 scale version is available to take measurements and the model comes out wrong anyway. Doubly egregious to my mind in 1/72 scale, where you can put a lot of details on the kit.