To those of you who showed constraint, and provided meaningful advice, I thank you.
Subsequent research, based upon your suggestions, led me to the Teleflex Marine BayStar Hydraulic Steering System. The following url provides extensive details...
According to the manufacturer, the X-5 is a "modular autopilot system for manual cable steered power boats with laden displacements of up to 4400 lbs". The section in quotes is directly from the Raymarine website.
I was just getting ready to install a Raymarine SmartPilot X-5, when I was told that they have all been recalled! And, there are, apparently, no other autopilots appropriate for mechanical systems?
Therefore, I am seeking recommendations for appropriate hydraulic steering for my 1993 Cruiser...