Most 0-2A aircraft came from Cessna with the belly skids. To my knowledge none of the civilian 337's nor the 0-2B aircraft had the belly skids installed. The skids are a fiberglass "Hat" section shape with a thick 1/4" aluminum plate on the bottom.
These skids were installed to save the belly, props and engines from damage during gear up landings. Skids can be installed on civilian 337 aircraft using a FAA 337 form. I have new and good used belly skids in stock.
Don Nieser
Commodore Aerospace Corp
405-503-4686
nieser.02.337parts@juno.com