If I have a GP330B installed and want to swap it out to a SCX20 can I just unplug the cable from the bottom of the GP330B and plug it into the SCX20 or do I need to drop a new cable?
It's a different cable. If the pull is really bad you might be able to cut off the GP330B connection and wire on a field connector. SCX20 uses standard device net NMEA 2000 micro connectors.