[Vwdiesel] '91 Jetta Voltage Regulator?

[geiser at execpc.com]

Hey guys,
Is there a separate voltage regulator on my '91 Jetta Ecodiesel, or is
that an internal part of the alternator?  My headlights kept getting
really bright this morning and the alternator belt would squeak like
it was really under load.  It was intermitant for a while, then it
just stayed that way.  It finally burned through the alternator belt
just as I was getting to work...
Just looking for an idea where to start to look for the problem...
Thanks,
Chris