Hi guys CH_123 showed interest in the IBM Model M 51G8572 this is the model that incorporated a speaker in the back of the keyboard.
I have a very nice example that swiped from the unused section of the IT Dept where my father works.
Internally its like any other model m but it has drainage channels like late model M's.
This board is dated 12-21-92 and was made by IBM.
Inside you see the speaker which is connected to the controller on the side
