1969 Dodge Dart Engine Stutter

OK get (if you don't) a charger that can bring the battery back up. Then re-run that test. The alternator may be OK, or it may be charging but unable to provide much output. If the battery is down that test may read low. Normally, with a good battery that is "up" doing the "full field" test will result in voltage needing to be watched as you bring up RPM. In other words, normally, as you bring RPM up to "highway cruise" the voltage may go on up to 16 and you need to start watching it. So you need to charge the battery and then figure roughly if the alternator seems to have some headroom.