In search of a wiper arm retainer clip (spring?). Don’t know the actual part name.

It resides in the arm next to the splines and holds the arm to the wiper transmission stud.
Exhaustive web search has turned up little info other than used on 68-72 Trico arms.
Hopefully someone has some otherwise junk wiper arms and could salvage this piece.
Please see attached image, courtesy of oldsfreak’s ebay listing.
Thanks, Matt