Michigan 2 blade, stainless,  9/16 shaft, 3/16 shear pin.  This wheel has had some major work done to it.  Looks trick.  6 1/2 X 10 1/2 pitch center of blade.  NOTE: In double checking this wheel it is a 9/16 shaft hole but a prop shaft goes in there very tight.  So, it may need to be reamed.  The other problem I am seeing is the shear on hole does not line up with a Merc prop shaft.  So, I am not sure what this was for?  Just don't want to mislead you.