While you're keeping us in the dark as to which one of your lovely old Buicks is sick, and showing a noise symtom we can only guess as to what is troubling her.
Yes the generator bearings if not given a drop of oil in the front and rear cup occasionally will protest with a squeal from time to time.
Brushes also in the generator have been known to speak out a bit also.
Why not take a long screwdriver and place it on both the water pump and generator and place your ear on the handle and listen. You should know in short order what part is seeking your attention.
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