Re: Need suggestions on SMALL 12 volt starter solenoid for 1955 RDE-17 25 Hp Johnson Home › Forum › Ask A Member › Need suggestions on SMALL 12 volt starter solenoid for 1955 RDE-17 25 Hp Johnson › Re: Need suggestions on SMALL 12 volt starter solenoid for 1955 RDE-17 25 Hp Johnson outbdnut2US Member - 1 Year (includes $3 online payment fee)Replies: 1705Topics: 91 August 2, 2018 at 6:50 pm #80555 A direct 12 volt replacement is Sierra 18-5807, but it will be the same size as the 6 volt one you are replacing. It was used in 35 and 40 HP Johnsons beginning in 1957 when they changed to 12 volts. Dave https://www.iboats.com/shop/sierra-18-5807-solenoid.html