Correct. All it knows/cares about is the current draw of the alternator field circuit. This is dependent on the windings of the rotor in the alternator. Early alternators (through about '80 or so) had field current draw of about 2.7A. Later ('81-up or so) had field current draw of about 4.4A. Years and current specs I give here are approximate; my spec books are far away at the moment. The changeover was done well after the 1970 change from electromechanical regulator controlling the feed side of the field circuit with one field wire connected to one isolated alternator brush (and the other brush grounded) to electronic regulator controlling the ground side of the field circuit with two field wires (and both brushes isolated). Early electronic regulators aren't rated for the higher amperage of the later rotors and so are not forward compatible; you'll burn out an early regulator using it with a late rotor. Later regulators are backward compatible since they are rated for the higher-amp rotors—though with today's fine made-in-China "quality", all bets are off. As for regulators compatible with the pre-1970 single-wire system that will also handle a high-current rotor: NAPA Echlin VR-1001 or Standard-BlueStreak VR-128.
A bigger problem with the higher output alternators is that you can fry your ammeter in the dash and associated wiring connections. That is a bad day.
The early A-bodies had standard original alternator output ratings of between 27A and 35A depending on year and equipment; 40A was the optional heavy-duty item. Output climbed over the years as equipment levels and electrical demand increased; the highest output alternators installed on regular production A-bodies was 65A, starting in '73 when equipped with the heated-grid backglass defogger (and available as an optional extra without the defogger).
J.C. Whitney used to have upgrade kits where you replace the field coils to give ~60A output.
Alternators do not have field coils; generators and starters do. Alternators have rotors and stators. Those JC Witless kits included a replacement stator. Yes, you get higher max output, but at the expense of low-RPM output, which is already a weak point of the Mopar alternators.
