buzzing external voltage regulator 72 K5 blazer

[RED72blazer]

Alright, in my 1972 blazer recently my charging system was overcharging. I traced it to a bad regulator. Replaced it. It charges fine. But there is a loud buzzing coming from my new regulator. Figured it was a bad new part. Replaced it. Still buzzing. Went to another brand. Still buzzing. So now just because. I changed the alternator. Still buzzing. Then I got a 80 dollar ac Delco regulator. Still buzzing. Today I cleaned all the grounds. Still buzzing. Anyone have any ideas on what is going on? This is getting tiresome. I do have a new wiring harness from M&H. I've had zero problems in 10 years or more with the stock system. I do not want to go to a 1 wire alternator or internal regulator. I just want the stock system to work. Any help would be great. Thanks