I'm in the market soon for a 60mm for my 500 c/m and am interested in the differences of the earlier "C" f/5.6 version versus the "C" f/3.5

Am I correct in assuming the later CF is the same optically as the C f/3.5 version but with the Prontor shutter and "updated" build quality?

Anyone have the old 5.6
I'll more than likely hold out for the 3.5 version but was curious about the 5.6 version nonetheless.