Unscrew old, screw in new. This was exactly the same as the one I had, the GRAY ST4000MK2 autopilot. Only thing I had to do was drill holes for it to fit on my wheel per number of spokes, but even the inside is already pre-set to accept the drilling. Simple. Plug and play with the old head unit, exactly as I wanted. No need to re-wire, though it does come with 30' of cable.Ridiculously expensive from Raymarine, especially since my old motor was fine, and I needed the plastic bits, bu..
