There should be a tag just below the inside vest pocket that gives good information, but may or may not tell the actual manufacturer. But that isn't all that important. What is important is that you have a WWII peacoat. @Astroboy posted a link to an excellent guide, written by the world's foremost authority in the dating of US Navy peacoats. There is a huge peacoat thread around here somewhere. I may merge this thread with the big thread just to keep everything together.