I have no idea, and that's my point. I don't know what's in there. The auto pilot works in "manual" mode -- set the heading, push auto and you're good to go. Turn the dial to adjust. Other than that, I'm clueless -- took me 10 minutes to get the cover off the vhf radio.kindof. Draw a picture of where you think you want to be, and then we can collectively connect the dots. Note that the Seatalk hub in my pic takes both ng and classic seatalk. It has a yellow connector, and a matching drop cable that is the big 3 pin moon. I didn't see an autopilot head unit in your mix. what is controlling it? the Garmin via 0183? the raychart? You need something to tell the autopilot to engage, or standby, or goto.
Just checked. Looks like I am running an old NMEA version as well. The radar had it connected. The GPS didn't have sea talk plugged in, but did use the power/nmea port. The raydata also has a nmea port that was being used in addition to the two sea talk ports.