Which sort of Mura C can do you have?
The position of the two fixing hole is the same in all C cans.
The outside diameter of the can bearing locates in the U bracket. Over the year there have been 3 different sizes of bearing used in C cans - 0.25 inch (6,35mm), 6 mm and 5mm outside diameter. More modern ones are 5mm od, so a U bracket made for modern C cans won't fit older motors unless the hole is opened out to fit the larger bearing.
The outside dimensions of the can are slightly different on some cans, many modern types of C cans use thinner metal which usually means slightly smaller outside dimensions. In theory this means the U bracket centre height needs to be slightly different to get the bottom of everything perfectly flat, in many cases the differance is too small to worry about