The Steam version will not take the Ubisoft v1.4 update. You will have to do the Steam v1.5 (
Silent Hunter®: Wolves of the Pacific U-Boat Missions), which can get rather confusing when attempting to mod the v1.5 version. There are not very many mods for the v1.3 of the game. They should be doing a "Thanksgiving" sale before too much longer, so watch for that.