High pitched noise from alternator

[Ron]

Well, I installed my freshly rebuilt alternator and took it for a test drive and it was still making the noise afterwards. Guessing I need to look elsewhere in the system? It did go away when turned the key on and off like Gluaisrothaii's did.

Did you try disconnecting the alternator?
Try the field wire first then the main. If still no luck, pull the fuses one at a time (there nay be more than one...)