Starter for 1951 MM Model U

Hello,
I have a 1951 model U with a 283 gas motor. Recently the starter went out and I have called all of our local parts stores trying to locat a replacement starter. But no one has been able to find one. I can purchase one for a 1954 "U" with 12 volt system. My tractor has been converted to 12 volts, would this starter work for my tractor?? Or does anyone know where I can find one? Any help would be greatly appreciated....