Hi @lstassen
I would say potentially 1962. Although this date seems reasonable, I am not aware of documented evidence for all machine made base markings....with a few exceptions.
Likely this is a Schenley brand decanter. If you search this forum on the word Schenley, you will see similar examples. I have associated D-9 with Schenley and a few other brands based on labeled examples.
Try searching eBay for "Schenley decanter" - you might find a match..