Kelly, your Luger is known as a transition variation. The inspectors stamps changed from DE/63 to SE/63 and yours was caught in the transition. The Y-Block Lugers I have recorded are marked with DE/63 & DE/63, the No Suffix Lugers are marked with SE/63 & SE/63. Thus, this change in inspection marks was made somewhere in the Z-Block.
So gentlemen, the suffix is a "Z"
