There was no OEM-from-Italy rearview mirror on the Ford Panteras. They were shipped to the USA without any outside mirrors.
it became common practice for the dealerships to install the rectangular mirrors that were then current to the Mustang and other Ford cars. Those mirrors are not side specific.
some dealerships also appear to have installed the “bullet-shaped” sport mirrors also used on Ford products.
The mirror in your photograph is neither of those mirrors.
The rectangular mirrors were always chromed. The bullet style mirrors were chromed or painted.
Larry