I also have a 3/45 Faz with no such markings on it. What does strike me is that yours has a cap on the fore end and mine does not. Could it be that No5's sent to tropical climates had the end caps retrofitted or the fore ends replaced by the individual countries own armories?
If only they could speak! How much different a life did these 2 carbines have made at the same factory in the same month.