Mooh,
   Your dad probably got that harp the same year, or the year after they started making them. They were designed by Mike Seeger, Maybelle Carter and another player I'd never heard of. They were first advertised in Sing Out! magazine and you could only get them directly from the factory. A few months later, the demand became greater and they started wholesaling them to stores. I have two of these, one from '66 that has wood chord bars and one from '67 with aluminum chord bars. I have converted them both to semi-diatonic 'harps, and they're my favourites.