73' duster wont start after dropping steering column

What likely happened with the "new" alternator is a sad but "popular" tale. CHECK WITH A MULTIMETER at the two small "push on" terminals which are the alternator field. The field circuit amounts to a simple electromagnet. NEITHER of those two should show continuity to ground. It may well be (It's happened!!) that the one field terminal is GROUNDED which should not be. This causes the "new" alternator to go to full output regardless of regulator.

The starting proplem, as detailed by OldManMopar, is likely linkage adjustment RE: the neutral safety switch.

If you have not done so, wander over to MyMopar and download a free 73 service manual (2 volumes) which got there because of a few guys right here.