I’ve read on reverb.com that rick serial starting with G means 1967. And starting with 9 would match 1996. For what you know, that makes sense?I think it's most likely we're all misreading the serial number. Instead of GAxxxx, could it be G(digit)xxxxx? That would make sense for 1996, and everything else I see here is consistent with that. I don't see any other obvious signs of fakery.
I'm pretty sure the 19th fret marker came and went over the years.
ps.: thanks a lot for all your help guys!