Your pistol appears to be early post war. It is in the serial number range from which the Austrian and West German Police contracts were drawn. Also pistols from this serial number range were sold on the commercial market, and also were marked with the Silesia, Akah, Geco & Norris markings.
I do not believe that it is Asutrian since you did not mention that there was any markings on the front of the grip. Very possibly it could be from the West German Police contract. Many of these pistols were imported into this country in the lte 60's and early 70's. (It was at this point in time that the Germans were again allowed to manufacture the P-38 and they wanted domestic firearms which is understandable.)
Originally these were imported with two matching numbered magazines and a matching numbered holster. Some did appear with a matching box instead of the holster.