My alternator died on 02 3L. Not sure it was actually voltage regulator or alternator itself as didn't have time to check.
Luckly, found used on craigslist (was from e39 530) for $80 and got her up and running again.

When the alternator died, OBC was showing between 9.5V~10.5V. After changed 13.5V. Still seems little low side, so in few weeks, I'll install the new voltage regulator just for peace of mind.