Don Nieser at Commodore (405-503-4686 or 722-4079,
nieser.02.337parts@juno.com) has done the SIDs, and shipped the diassembled aircraft to Australia or NZ. He may have an aircraft for sale, or look online for one. Most (all?) 337s in private use have NOT had the SIDs done because it's not mandatory.
Ernie