Capt. JG wrote:
According to the manual, the interface "may be used with any radio
navigation system that uses NMEA the 0180, 0181, or 0183 standard," so it
looks like I should be good to go....

My previous boat came with the old Nautec Autohelm 5000 auto pilot,
circa 1985. I don't know what inputs it took. I replaced it with a
ST4000 in 1994 and it was certainly NMEA compatible.