Another common problem least where road salt is used is the brushes wear down but more importantly the springs behind them rust/corrode leaving the brush or brushes with very little or no pressure pushing em against the armature. Brush guides get fowled with crap sometimes too, brush no longer able to move toward armature as they wear down. Once contact of one or both brushes is lost, that creates a no charge condition such as you have.

Voltage reg can be serviced with alternator in place on motor however if original factory engine hosting bracket is still in place on the 460, its a little tight to get to the 4 torx screws holding the VR in place. Get em out, put em back in, easier if remove alt.

Brushes and their springs are easy to inspect/replace. If you do pull it off the back of the Alt you'll need something hold brushes up in place when putting the VR back on the Alt. A common strip type feeler gauge works perfect, one thick enough have little back bone is all it takes.

NAPA AUTO PARTS

Naturally you can buy the whole voltage reg if needed rather then just the brushes and spring kit. However the bulk if it is plastic once those parts have been removed.