'67 Dart - No stop lights, turn signals on but don't flash

If you remove the flasher and the turn signals quit lighting up, then you have the right one. Try touching the flasher wires together with a turn signal on and the ignition on & see if the lights light, just for a double check.

You could have a second bad flasher you are substituting. People say double faults are rare, but seems like they happen to me with some frequency. Just bad luck I guess.