There is no "year" per say for that mirror. It all depended on the particular VW dealership that each car was sold at that determined what style mirrors, or any accessory for that matter, were placed on the cars. That is why there are so many different styles around. If you notice in the VW parts catalogs they are sold for basically any pre-67 VW.
Can you post a photo of it, with the box here?
Larry
Enjoy life to the fullest - in a VINTAGE VW