Bread,
I have the old bell housing mounts from my 1965 and 1966 C10. They are in good shape. I wonder if they would be correct. Send me a PM with your email and I will send you photos with dimensions.
Also, your bell has a cast mark on the driver's side - L6 56. I think that means it was cast on December 6, 1956.
(L is the 12th letter of the alphabet).
