Thanks for the help so far. The e120 plug
for nmea0183 is in use by the cable that says seatalk. The autopilot is autohelm/raymarine. The module i found under the bed appears to be http://www.raymarine.com/view/?id=5534
E85001 mutifunction seatalk converter.
If i take nmea0183 plugs and make a t adding with 2 the same colors and the third the correct matching to the simrad, and plug
this in at the e120 in the back.....should that work