My pile of parts that's turning into bikes came with 2 engines. Neither set of cases had ever been stamped. Per others on this forum, they'd have been stamped by the dealer when replacing them, but many times they just didn't bother. So really, even matching numbers may not mean much any more. With a set of letter/number punches, anyone could stamp these cases. Makes me wonder how many original "matching numbers" bikes are really all original??? If cases were replaced and stamped by a dealer 50 years ago, is it original?