Not so sure your speaking with all facts in place "Autolite". My radiator fits every criteria for being most probably original to the car (Oct 18 65 or thereabouts build date 18K, with a 9 65 stamping on the top). The radiator was sent out for repair on 12/14/82, as the gas station "Green Shell" etched their name on the top of the tank with that date- a common practice when a radiator was sent out for repair at the time (told to me by a gentleman who saw the etching on my radiator and runs an actual radiator rebuild shop out of St.Louis, whom I met at the 2016 Carlisle Ford Nationals). In other words, the radiator has a seemingly long history with the car that predates these repro tags even.
Kevin Marti's book clearly shows the C6ZE G2 code was used on 1966 radiators with a Manual trans, pg. 105 of his code book.
Even the sources you cite, Year One and Mustangs Unlimited say that they were used on about 50% of the cars. There is no code stamped on the side of my radiator support, so this is the likely tag put there at time of production, as at least half of them had, depending on what vendor made them.
I highly doubt mine is a repro, previous owner owned the car from the early 80's to 2010 when I picked it up. Not likely a repro tag on this one.
If you claim this tag was never used by Ford, what sources of information are you using for this opinion?
