The Dufour 34 owners Facebook group has a some good information on this. We also have to fit an autopilot to our 34p at some point. Seatalk Vs seatalkNG isn’t so bad as the converter is cheap and plug and play.
You have roughly three options which you could do a bit of mix and matching between-
The cheapest and simplest is to get a Raymarine EV-100 wheel pilot pack. This uses seatalkNG so it can speak to your current instruments to get wind and boatspeed data if you get a seatalk to seatalkNG converter. The upsides are much easier installation but downsides are the wheel drive unit isn’t very quick or powerful so for for motoring and basic sailing but not up to much more. It also doesn’t need a rudder sensor and draws compatively little power.
The factory autopilot install used a rotary drive with a chain to the wheel axle. You can’t really buy a pack for this as one so DIY won’t be that easy and the parts you can buy are more expensive as you need a more powerful control unit than the ev100 to drive the rotary unit. You also need to fit a rudder sensor, chain, and put a few holes in the boat for the drive unit mounting.
The most complex option is similar to above but you fit a bracket to the quadrant and put a linear drive unit or hydraulic ram in the starboard aft cabin and cut a hole through the deck to get the arm through to mount the bal socket on the bracket on the aft end of the quadrant. Then waterproof with a gasket. A lot more work, a lot more power draw but a lot more performance.
You can do it a bit more cheaply if you use older generation parts like the st6000 type control heads and the S1/2/3 control units but the modern compass and software is so much better it’s a false economy I think.