That's a bit too broad of a question, but I'll do my best...A radar dome directly connected to the old 7" will not work with a 10.4" display. If you have a radar dome, it'll have to remain being connected to a 7" display or replaced with one that works with the 10.4". The 10.4" has an extra NMEA0183 port...Data2 is NMEA0183 in/out on 10.4" and Data2 on the 7" is for heading input only (like Data3 on 10.4"). That's basically it, other than the obvious larger size screen on the 10.4".