If you are willing to open the package and slide a blade partway out, you should be able to read the date code and then you will have a year. However we can make some guesses from the packaging. The 1960s and 1970s packages were mostly metal, like the Spoilers, or plastic with labeling molded in. I think the first plastic packages in this style, with adhesive labels, came in ca. 1985 and stuck around until the 1990s or early 2000s.
As far as I know that package is not particularly collectible, so I would open it up and try one. They may shave well.