Plastic, specifically PET, bottles were introduced in the mid 1980s but this could be as late as the mid-1990s. UDV (now Diageo) would have been using the Medley UPC and Owensboro address until 1995, when it sold the Owensboro bottling and maturation facility to Barton. I'm not aware of Barton ever having the Antique label. I'm not sure who has it now. Could be BT, which acquired that Owensboro facility from Barton a few years ago, in which case this could be very recent. Another possibility is that Seagram's unloaded Antique when it dumped all of its straight bourbons sold in the USA in, I think, 1987 or thereabouts. Medley might have picked it up and through Medley, via Glenmore, it became part of UDV, which would place this bottle between 1987 and 1995.
THANK YOU! Quite informative.
Lucky me, I know a guy in Kentucky who wants these bottles... wonder what I could request as a trade