What test instrument is BNC jumper the from?

[graybeard]

This BNC jumper came with many RF adapters & terminations from disassembled test racks.  It looks like it was part a piece of test gear.
The BNC centers are exactly 1.8" apart.
A part number on on of the BNC connector is 28AU100-1
The date code is 4991 which I assume means the 49th week of 1991.
Do you have any idea what this is from?

Thank you,
Chris