http://www.seastarsolutions.com/products/hydraulic-new/fittings-new/
GRAINGER
MCMASTER CARR
Seastar lists the fittings as 3/8 compression 9/16"-24 extra fine thread. Stainless or brass.
Do you have any pipe fitter friends in Corning?
Loctite PST on pipe threads
1/4" NPT on the helm