I have a 1967 John. 60 Hp, Mech Shift.<br />I have not opened up the gear case yet, but plan to in order replace the clutch dog. I am wondering about interchange the gears. My book describes the Heavy Duty gear case as having interchagable gears. I have the standard gear case though, and the gears are never mentioned as being swapable. Has anyone successfully switched these two gears? OR can anyone tell me what the differenece is between the F & R gear?<br /><br />Thanks, Tom