1965 Dodge Dart Charger

Yes, there's only one resonator listed and it's the #2660 445. Please read the comments I posted, not just the clip I posted from the FPC:

(…) as particular applications grew older and demand dropped, often the more expensive aluminised unit would be dropped and only the cheaper galvanised option would remain (or mufflers previously available only as aluminised would be downgraded to galvanised) to compete with the non-Mopar aftermarket muffler offerings on price.