The Redfield Artel scope was produced during 1968 and 1969 by Redfield in Denver, Colorado with the ART mount built by Rock Island and Frankford Arsenal. This is the first production version of the first practical auto-ranging telescope and mount designed by Jim Leatherwood.
In order to get this design into production and into the field as soon as possible, Leatherwood did not wait to sell his patents but rather signed them over to the DOD in 1965. The Limited Warfare Lab commissioned Redfield to build the optics at their Denver plant. They were then shipped to Rock Island or Frankford Arsenal to be installed in the mounts. The number stamped on the mount originally matched the last 4 digits of the rifle that the scope was paired with, but not necessarily mounted on.
The original prototype for the ART system can be seen in "The Long Range War" by Peter Senich on page 108.