Here is my latest model 41 Extendible Front Sight (EFS)!
I could tell by the addition of proof marks that this model 41 had spent time in Germany. In front of the serial number is a Nitro proof, 68, and an antler. The barrel and the slide also are stamped with a Nitro proof. The 41 was "Proofed" in Ulm as signified by the antler in 1968.
While cleaning the 41 I also found the importer's stamp "WAFFEN-WALTHER BAD DÜRKHEIM" under the left grip panel.