Talking to the person who gave me the motor, It had been put inside a shed at a remote cabin on the south end of Kodiak Island Alaska, He figured it had been there for decades until he purchased the property. Last season he had a salmon fishing boat bring it to town He tride to use it for the first time this past June, said it was very hard to start, & Had very little power. Using a digital caliper I took measurements of a 1985 20 HP, it measured 1.044 inch or 36.5mm, a 1989 15 hp measured 25.55 mm or 1.006 inch, The 35 motor in question measured 22.77mm or 0.895 inches, 3mm smaller than a 15hp intake, Also I found a part # 390655 , However it looks as this part# has been superseded @ least twice. kodi