On my M135, I ran a wire off one battery to a junction block inside the cab. That gives 12 volts. I took the large coil wound resistor out of the distributor, connected the distributor input wire to the appropriate side of the coil, ran a wire from my 12v junction block to a key switch in the dash, then to an ignition voltage dropping resistor like Mopar uses and then to the distributor input wire. This puts about 8 volts, the customary power for a distributor to it. The large original resistor in the distributor drops the 24 volts down to around this value anyway. Run the normal point and condensor set and it works fine. Then you can put any aftermarket tach in it, wire in 12 v turn signals, etc. from the block. You can add inline fuses as you wish from the block. I drilled a hole in the side of the top distributor metal cover, put a grommet in it for a wire to go through, and ran my tach pickup wire through the grommet and attached it to the coil in the required manner. This way the cap can be removed by feeding wire through the grommet as you lift the cap, and pulled back carefully as you replace the cap.
Regards Marti
