I believe 37 Fleetwood is correct that the package was offered as a dealer option package. Ulf, 65DartCharger is probably the most knowledgeable on the subject.
Interestingly, the package (273 HiPo, lt. yellow (special order 999) with black vinyl top and white/gold interior and 13" Cragars) could be purchased WITHOUT the Dart Charger emblems. I owned one purchased from Chuck Hutton Dodge in Columbus, GA. The 13" Cragars were unique in that the rims were chromed steel and the spokes were polished aluminum.
Galen Grovier (sp?) has no interest in these cars because there was no fender tag code for them so there is no way to verify a genuine Dart Charger.