My memory isn't as good as it used to be. Does your Dart have a old style points regulator or did it come from the factory with an electronic regulator?
The one shown is for the electronic regulator that has two field terminals. It could be made to work on the Dart pretty easy if it is the old style points regulator.
No matter what it had you should run a heavier gauge wire from the output of the alternator directly to the battery side of the starter relay and eliminate the ammeter in your dash as the higher output of this alternator will burn up the factory ammeter and wiring.