I'm pretty sure that a 1984 with MPI (i.e. Turbo setup) had the regulator inside the power module.
Additional: How many wires hook up to the back of your alternator? If it has the FLD connection you have an externally regulated alternator and per my first assumption, it is probably in the Power Module. I only ask this question because there were a few rare instances (so I have been told) that Chrysler used internally regulated alternators, but I believe that was only on the imports which would not be applicable in your case.
Additional: How many wires hook up to the back of your alternator? If it has the FLD connection you have an externally regulated alternator and per my first assumption, it is probably in the Power Module. I only ask this question because there were a few rare instances (so I have been told) that Chrysler used internally regulated alternators, but I believe that was only on the imports which would not be applicable in your case.