@Community Member posted:
The serial number is in the same place on the railed G48 and 43X.
Most European pistols have numbers on frame slide and barrel , and Glocks out of Europe have has serial numbers on the frame for decades.
Hmm. I went to an auction house and gunstore in Vienna three years ago and looked at several Glocks without serial numbers on the frames. It may take a couple of days, but I'll try and verify with friends in Austria