so here is my ppk

what you see here in the ejection port is not the year it was made ( but very likely it was the year this pistol was made)
this are the proofmarks of the proofhouse in Ulm/germany and they read as follow:
"nitroproof in 1966 in the proofhouse ulm"
the year 1966 is the year this pistol was proofed

such a proof is mandatory if you want to sell this pistol in CIP member state like germany. you dont realy need it for sellling the pistol in the united staates.