Apologies for the double posting; this subject spills over from Vintage.
Re:

W123 280E/CE, &/or W126 280SE
Wanted:
Pictures of the throttle linkage from the black owner's Parts Book (aka Catalog) for the above models.
The wanted pages are for Group 7, and Group 30.

The part in question that I am searching for is a plastic isolating piece that interfaces between the longitudinal shaft and the remainder of the engine-mounted throttle linkage. In the FSM it is shown as a white plastic piece, and might loosely be described as being "butterfly" shaped.
The FSM does not provide any part # clues; the owner's Parts Book may provide a starting point.
The Part # is the objective.

Is this what you're looking for?
https://www.pelicanparts.com/More_Info/1100720038.htm?pn=110-072-00-38-M22

RealOEM has an exploded view of various throttle linkages:
https://nemigaparts.com/cat_spares/epc/mercedes/1/m/110985/032/07/001/?chasis=11602468N

That certainly would appear to be the item; it's hard to tell when there aren't even any pieces left.

We went through that with a friend's 280SL. When they crumble away it leaves a HUGE amount of slop in the throttle linkage.