I'm not sure if I'm reading your question correctly, but if you're asking if GLL can be output on port 2 to provide heading...then no; GLL is position data only. If you're asking if HDG and GLL can be output on data 2, then...yes it can, but if HDG is being output to something other than a NMEA display (i.e. RD30 or RD33), then it's highly recommended that heading data come directly from the heading source. To bring it in to a NN2 and re-output it to a device for use with ARPA or AIS would not work because the heading data will not output fast enough from the NN2.