Hydraulic steering

[Garrison]

I am looking to replace my hydraulic steering with a new Sea Star helm for smoother steering. Does anyone know what size shaft I would need for my '74 20 c/c? They offer 1.7 and 2.4. I am trying not to take my wheel off to check the number on the shaft, until I get the new unit and replace it. Thanks for any advice.

[Old'sCool]

Doesn't that refer to the hyd. capacity? or flow?