Machinist set up, layout bar TOOL milling jig ???????????????

Description

I'M NOT SURE WHAT THIS IS OR CALLED. I GOT IN A BUNCH OF MACHINE TOOLS YEARS AGO AND HAS BEEN IN MY CHEST A LONG TIME AND GIVING UP THE HOBBY. I'VE SHOWED TO SOME MACHINISTS AND NOBODY SEEMS TO KNOW WHAT IT MAY HAVE BEEN USED FOR. IT IS WELL MADE AND VERY FINE FINISHED AS IF MADE BY A COMMERCIAL MANUFACTURER. IT IS JUST SHORT OF 15 INCHES IN LENGTH.THE 2 BALL ENDS UNSCREW AND THE BALL SHAFTS FIT SNUGLY IN THE HOLES. WHEN INSERTED LESS THAN 1/1000 OF PLAY BETWEEN THEM. THE HOLES IN BAR ARE .250 INCHES APART AND 1/2" IN DIAMETER . THE BALLS ARE 1 INCH DIAMETER. THE BALL SHAFTS ARE THREADED SO THEY SCREW IN THE END OF BAR FOR STORAGE. THERE IS A COMPOSITE SLEEVE THAT SLIDES OVER THE CENTER OF THE BAR THAT HAS A SLIGHT RECESS IN CENTER TO HOLD IN PLACE AND KEEP BAR OFF OF SURFACE IT MAY BE ON WHEN THEY ARE INSTALLED. IT WEIGHS JUST SHORT OF 2 POUNDS.
IF ANYONE KNOWS WHAT THIS IS I WOULD APPRECIATE LETTING ME KNOW. I HAVE NO IDEA OF VALUE OTHER THAN IT WOULD BE EXPENSIVE AS TO THE QUALITY & PRECISION THAT IT IS MADE.
IT MAY HAVE BEEN A ONE OF A TYPE THING MADE BUT I BELIEVE IT TO BE COMMERCIALLY PRODUCED AS TO THE QUALITY.
THE FELLOWS ESTATE WHERE I BOUGHT IT DIDN'T HAVE THE KIND OF EQUIPMENT TO PRODUCE IT AT HIS HOME. PROBABLY LOOKED AT IT A THOUSAND TIMES AND ALWAYS WONDERED WHAT IT WAS MADE FOR. HE DID WORK AT A COMMERCIAL MACHINE SHOP SO MAYBE IT COULD HAVE BEEN MADE THERE IF IT IS A ONE OF A KIND. THANKS FOR LOOKING.