two post (small terminals) solenoids have a post (right side-small terminal) that needs 12 volts to power the solenoid, the other (left side small terminal) is used in conjuction with a neutral safety switch, also a clutch pedal safety switch. Your original solenoid was powered all the time and used the small terminal to the dash starter push button which grounded the solenoid to work. I changed my 41 to 12 volts and powered the right side post and ran the other post to the original stater push button,which grounds the solenoid to make it work, the battery cable go to the terminal on the right side, usually marked "batt"