The brochure states that one should look for the gios name stamped in bb, seat stays, fork ends etc... I have an 83 that has all those stampings but no serial number. The reason for the lack of the serial number was supposedly that they were trying to avoid Italian duties by not accounting for all the frames they produced. I believe that to be the case. Also the year for the first compact is I believe 1988. I have one of those too and it additionally has the gios name in the head tube lugs, which my earlier model does not have. I understand that the original fakes were in fact Gios bikes coming out of their own factory. Perhaps they concocted the story to avoid the Italian government's retribution for their own shenanigans.It seems unlikely that someone could have produced all the correct lugs and the obvious good craftmanship and not have been the Gios factory doing it.
Garth Libre in Miami Fl USA