True for 1990 and before - they used Delco alternators (typical for AMC - Delco or Motorola) and the Delco SI and CS series have internal regulators.
Chrysler uses Nippondenso alternators, and they use external regulators. 1991-up has the regulator circuit in the PCM.
However, it's entirely possible you've got a ground floating. Can you reproduce the problem while sitting still? If you can, do this:
Shut down.
Take out your booster cables, and connect the engine block (as close to the alternator as possible) directly to the battery - post. Watch for "mechanical interference" (getting the booster cable caught in moving parts is a Very Bad Thing (tm))
Restart, and try to reproduce the problem again. If you cannot, it was probably a ground issue - check, clean and/or service as necessary. If you can, move the engine end of the cable to a clean spot on the chassis and repeat - if that solves the issue, then check your chassis grounds and clean/service as necessary.
This costs a lot less than buying parts, and problems like this are often fixed incidental to replacing the part anyhow. Therefore, you don't know that you actually solved the wrong problem! This would probably take you about a half-hour, and this is the sort of test that costs nothing but your time one after-noon. If enhancing the ground doesn't fix it, then you know - and can replace parts with confidence that you actually do have to spend the money on them.