I was able to call Clausing and give them the serial numbers of both my 8520 mill (1963) and my 16SC drill press (1961) and they were able to give me the year of manufacture. I don't have the phone number but you can google it. They also emailed me the appropriate parts list for the drill press. The parts list for the mill is available at Vintage Machinery if you don't already have it.Was it this group that i saw place where you could look up your mill serial numbers and see when the mill was made?