McCoy Prop Washer.  The inner diameter is 3/16".  The outer diameter is 15/16".  (I measured the inner diameter by using a drill bit.)  Unfortunately I do not know which engine these fit.

Please note that the hole for the crankshaft seems to not be perfectly round.  This appears to occurred at the factory, given how smooth the backside of the hole is.  I do not know if this will affect anything. Please note that the washer has a small bit surface rust.