It appears to be about 9.75" in OADiameter.
A little wire brushing revealed what appears to be "TRB" stamped on the back.
Taking pictures of the back side may exceed my interest at $5 plus
shipping. But, if necessary, I can.
You can't ID it from the front pic and OAD dimension?
What kind of parts guy are you?
Suggested annual donation $12.75