Initially, only 30 GNX-603T GN-X were produced, but more units were manufactured after the United Nation Forces' (UN Forces) victory over the Celestial Being. These newly made GN-X are known as the late production type and they played a significant role as the world unifies, battling forces that were against the disbandment of each nation's military that was part of the unification process. It was during this period that the GNX-604T Advanced GN-X was developed based on requests from the battlefields. An improved version of the late production type GN-X, the Advanced GN-X is a custom machine mainly provided to the UN Forces' ace pilots and produced in limited numbers, constituting less than 3% of the GN-'s overall production run.
Appearance-wise, the Advanced GN-X's basic structure is almost the same as the GN-X's, except for changes to the head, shoulders and thighs. The added compound antenna on the head improves the mobile suit's search and communication abilities, as well as enable the control of GN Drive Tau-type mobile suits under its command.