Hi Dave,
Absolutely interesting. What we have to figure out is why the toggle link have the last three digits engraved. It should be something related to the production phases but we need to discover when during the production phase it was necessary to do this. Should be also useful to know around which serial number Mauser started this.
Concerning the date, if your pistol is FBM marked it doesn't have the date stamped. The date is stamped on the pistol when it was tested in Ulm to be sell in Europe.
Usually the pistol imported by Interarms are simply tested by Mauser and not by the Ulm District Proofhouse.
Thank you for the information.
Ciao
Mauro