I have a 1996 Nissan 4x4 D21 Pickup and the charging system has
suddenly quit working.  It 'appears' that it has a separate voltage
regulator from the alternator (and the alternator's a bear to get at
from the top).  Can anyone give me any pointers in identifying which
one is causing the problem before I just start swapping parts?
Checked and charged the battery completely after a hydrometer test
showed it needed a re-charge (and it was about dead).  Charging it for
several hours has put a good charge back into it but upon starting it,
the gauge indicates that it's not charging.

Thanks for any help,

John