On Thu, 1 Feb 2007 18:48:55 -0500, "Roger Long"
wrote:

Never mind. I found a list at:

http://aprs.gids.nl/nmea/#allgp

I'd still be interested in hearing about anyone's experience with such a
hook up.

Most auto pilots want to know cross track error ($GPXTE), course over
ground ($GPVTG) and bearing to mark ($GPBWC).

I read throug the Garmin manual online and can't find any mention of
cross track error. I'd call Garmin tech support.