ok went to a local pick n pull. found a 2000 ranger and yanked the alternator. the part (motorcraft
)had a sticker on it saying it was built in '05... so it must have been a replacement. $25 .. dead cheap in my opinion.
long story short no more whistle!
the old alternator must have dry bearings.. when i got it off and spun it it was making a nasty kind of grinding sound.. maybe i'll take it apart some day...
by the way i did stick a multimeter on the battery .. the new alt. putting out juice nicely as it should