Bob Hovey's site does a good job of monitoring the Gran Criteriums from both Italy and the USA.
I have a Milan made GC from 1970. Ken Denny will claim 1969. The GC continued in Italy even after Carlsbad production started. Surprises turn up as to how long the model continued, it appears even after the Prestige was introduced. The surprise to me were Italian GC's with Alberto's signature transfer.