That is the only problem with a Steam game, is you have to stick with Steam for that game, but the v1.5 "update" on steam is:
Silent Hunter®: Wolves of the Pacific U-Boat Missions
That is the US store link, currently at $10 (Ok, $9.99) US. It does go "on sale" every now and then.
In the meantime, using a link through SubSim here, you can download the "Gold" version, which has v1.5 Uboat missions all-inclusive:
Silent Hunter: Wolves Of The Pacific - Gold Edition [Download]
currently at $20 ($19.99) US, but will usually match Steam when they go "on sale"... Pick yer poison.
Which ever way you go though, do not install the game under the Windows "Program Files" folders, but rather make your own install folder. If using Steam, you would have to make a new Library folder, which can get complicated.
