what is this?

I took off my rear drums on my 73 dart and when I took off the drum this piece fell out, I see where it goes but dont know what its for, and don't know what it is so I can get a new one. My dart has factory front disc brakes.

Can I raid this part off of earlier model car? like the 68 cuda sitting at my grandpas place?


That piece comes in the hardware kit for the rear brakes. Yours should be 10" diameter.