I just looked at the 72 Dart and it has one hole for the light/wire, and a locating pin on the indicator.
Two holes like mtrhead posted.
Since the indicator is on the car I can't get an exact for you, but since I F'ed up on the holes I went out and measured where the light fixture itself is.
1 and 5/16 from the fender extension seam to the tip of the fixture.
13/16 from the hood side fender edge.