Thank you Neil for your comments regarding that car.
The french description, and also the english (quite litteral: phare = beacon) translation raise a few questions:
The car being exhibited is one of the rare cars, nicknamed fanalone (great beacons), which were made in 1969-1970 according to the specifications of factory cars (steel body with aluminium sliding roofs).
I think you answered those questions perfectly! Another example of misleading descriptions, that confirms the absolute necessity of thoroughly researching cars offered (at auctions or at dealers).