Hopefully this may help someone...
Finally decided to isolate buzzing noise that would start as soon as ignition key was turned to the on position and continued to sound once engine started and running. Sound turned to a high frequency squeal when vehicle was put in reverse gear. Sound was coming from right side of center console..

Initially thought I had a bad servo, so I started removing dash, etc... After removing center console plate and ashtray assembly I found the culprit. Stuffed under the console was a motorola speaker that went to phone system... Unplugged speaker and problem solved...of course, 8 months later after sound first observed...

 

Is this an aftermarket speaker or something that came with the car?

 

Considering the installation configuration, components just laying loose on top of floorboard and not in a cradle or mounted I would assume it is " aftermarket ". I will take pics tomorrow and post ....