Mine was in a hybrid type. It still had a bolt on fan shroud but used twin piston rings with the slits in the cylinder. It was by MTD (who made these Ryobi engines). I would suspect than any newer ryobi type would have the newer type rod.
See this link for the newer piston/rod -

From:
http://www.ereplacementparts.com/pis...-p-282359.html