Hi Divertom, welcome to boatmad.
To be honest, i've not personaly heard of Indemar steering, tho that doesn't actually mean much.
I'm sure a trip down to your local hydraulic stockist, armed with samples of what you have, will get some answers faily quickly, even if it's just to say "we ain't got none", they may be able to identify the threads/fittings for you.
"I Agree with everything you say really!" - John Cooke to Jon Fuller - 26-01-2013