---

Basically immaterial for shaft length.
We can't measure that accurately.
They tell us 20" Long Shaft, 25" Xtra Long Shaft, etc.

We go by tested and proven heights on mounting.
1 hole up, two holes up, etc.
Regardless of brand, year, etc...

Don't complicate this more then it needs to be.
KISS......... Keep It Simple Simon

Drill the upper Black and lower Green holes and be done with it.
Done.
Now you don't have to think about it anymore.

Congratulations.