Differences between 50/60/70 hp lower units between 1988 and 1989?

[ShoestringMariner]

I've read the sticky on lower unit compatibility though I couldn't see anything on driveshaft spline count for either years.

Any other differences?

 

[Faztbullet]

Same units just different splines..89 up fine spline

 

[racerone]

We talk 3 cylinder motors here.----Agreed the 89 and newer are fine spline on top of driveshaft.

 

[ShoestringMariner]

Thanks guys, I’m assuming the 17 spline is the fine spline?

is it easy to swap shafts?

 

[jakedaawg]

Yes

 

[jakedaawg]

I should preface that, it's easy if you know what you are doing or have the manual and the tools. You may need to adjust shims.