i am working on a1960 johnson 75hp the gears were worn out and it began jumping out of gear so i came up on a 1963 75hp elect shift which i exchanged but when i try to engage the gear both foward and reverse no noticeable noise this unit could of been bad also the input shaft and the prop shaft turns freely also would like to know what the difference in the 100hp and the 75hp same cubic inch displacement but the 100hp came with 4barrel?
