Re: 1957 Johnson 10hp and 18hp gears Home › Forum › Ask A Member › 1957 Johnson 10hp and 18hp gears › Re: 1957 Johnson 10hp and 18hp gears frankrUS Member - 1 Year (includes $3 online payment fee)Replies: 6715Topics: 51 July 2, 2018 at 3:02 pm #78891 It would appear there is some conflicting information out there somewhere. My statement was based on the 1957 Johnson brochure. .572 vs .578 ratios. Not saying it was correct, though.