I remember reading about this a while back and found the link. It may be NLA. They're also known as breakout boxes or test-tee's - we call them test tee's in work because the schematic looks like a T, and the breakout boxes, or BOB is more of a dead end for the signal. The T allows you to monitor the signal in question while it is in the circuit.
They are very expensive $800-1600, but can be made if you can get a M and F 35 pin connector and a budd or plastic box (newark).
If you do it yourself, I don't know if buffering the signal in the tip or banana (pomona) jack path is a good idea.
DME breakout box - where can I get one?
HTH