Re: steering
Mercury dealers can't help you?? Oh well.
Anyhow, you can replace the whole system with a Teleflex, rack & pinion system would be the closest to what you have, but rotary systems will work too, depending on available space. Understand it is not a direct replacement, drilling and cutting may be required. In fact, if I remember correctly, even the steering wheel will need to be replaced.
Teleflex sold here at iboats!!!