I think it is from 1972-1976, I have only seen 1 other one and it was on ebay, I forgot to bid on it but it sold for around $50 and it was not nearly as nice as mine but I still wanted it, it also didn't have any brackets to mount it like mine.
I shouldn't have the responsibility of owning something like that anyway. I just do something stupid like mount it on Baby! Do they go in front of or beside the side mirror?