Keith
I had a new rear hub made for my 1911 sometime ago as the original had cracked around the threaded flange onto which the sprocket locates. I still have the original with the crack which I could send to you for reference if that helps. I am assuming that the hub will be the same design. I am unsure whether the machine shop I used still has the drawings but I could make inquiries for you if it might help.
Regards
Lewis