Hi it has been a long time since I visited this forem. I have a D47U Cat that I have changed the windings in the generator to make it 12 volt. I have done this on a 1960 70D Cat grader and it worked fine. The gen on the grader has 2 brushes, and the D4 has three. I can't get the D4 gen to stable out. It will charge from 14V to 3V and anywhere in between. I have also burned up several voltage reg's. Can anyone give me a little help? Thanks Mike