My truck has developed a high pitched noise that sounds
like the noise you might hear on your stereo speakers
if you didn't have a RF filter. The noise seems to
follow the speed of the motor and as best I can tell
it's coming from the alternator. It's still putting out
13.8v to the battery at this point but I'm curious
what would be causing the sound and how long I should
expect it to last now? I should note that I recently
replaced the drive belts. Thanks for any clues.

Regards,
Indy