I looked in all my skymaster parts catalogs up to 1977's and the 1973-1980 P337's and they all use the same wing jack pad P/N 1400110-2. I have new ones for sale.
Don Nieser
Commodore Aerospace Corp
6221 Commodore Lane
Oklahoma City OK 73162
405-722-4079 phone and FAX
405-503-4686 hangar cell phone
nieser.02.337parts@juno.com