https://www.portapilot.com/
Years ago, before GPS, we were on a friend's sailboat and it had this gadget looked like a shock absorber, . One end attached to the tiller and other the boat.
It would expand and contract to hold a basic constant heading.
This seems to be the GA version.
That all aside, the 337 is soooo table when trimmed......
Over the years I picked up servos and even Navomatic CPUs (and I use the term 'CPU' very loosely), to have enough bits and pieces. It's basically a collection of analog feedback 'chopper' circuits that ue pos/neg pulses to pass analog signals.
Eventually the CPU capacitors got snarky in the CPU so I pulled the whole thing and sent off to autopilots central for OH recert on their bench.