Your PP was made at the Thuringia complex as shown on the slide, so it is a WWII pistol. Could be a Postal or Railway WWII Police pistol. Best to contact Dieter Marschall at the Walther forum. He is a Walther authority and will tell you exactly what you have. I lost his email address but maybe one of the members can post it. I contacted him a while back regarding my bottom mag release Thuringia PP in .380. He researched it and advised that it was made between 1940-41 in a small batch for the Luftwaffe.