Broken down college kid

Hey all, I have a '74 Dart sport with a slant six and is my only means of transportation. I was driving to a friends house across town the other night and noticed my amp meter gauge was reading in the -40 side instead of directly at top center as usual. I also noticed the dash lights were much dimmer than originally. So coming up to a stop light my car stalled, I started it back up and stalled again. I got it started again luckily. On my way to my friends I turned a corner and the car died again, but before that the engine felt like it was misfiring when I would try to accelerate, it would stutter and kind of pause. I got my car started up once again and I parked it in my friends driveway finally. I go back out to it some time later to start it and it wouldn't start at all.

Long story short, I took the alternator off had it checked out, it failed the test at Advance Auto, as well as an alternator shop. I got a newer alternator to replace it, hooked it up and the engine still won't start... Could this be something else wrong such as a voltage regulator. One thing I forgot to do before I left after replacing the alternator was pushing the seat belt interlock button. Would that button need to be pushed to reset the mechanism? That keeps the car from starting correct? Thanks for any help