Although Puch and Austro-Daimler made 531-framed bikes, only the A-D had a Superleicht model (I think). Yours is probably a Puch Olympian or Mistral. Both bike brands were by Steyr-Daimler-Puch but A-D had the cachet at the time and a Puch-named frame didn't get the same respect, even if it was every bit as good a bike.