1965 Dodge Dart Charger

That's a 1961 voltage regulator, part number 2095 700. The 1960 models equipped with alternators (Valiant + Imperial) used 1889 960, and starting in '62 the P/N was 2098 300 (which superseded the '60 and '61 items). Can't say I've ever seen a rivet as you show. Looks like it would prevent the regulator cover being removed, which is strange since these regulators were designed and intended to be adjusted in the field -- there's an enormous amount of how-to info in the service manuals. Perhaps this was a Mopar rebuilt regulator (such things did exist) done in '62 or early '63.