Custom Force X
The original custom force was simply the original mod with the ability to substitue your own heroes instead of the built-ins.
Yellow Lantern's upgrade goes far beyond that. In addition to adding FFX to the original Custom Force, YL also added many FFX attrbutes and swaps to the regular FF characters and add new recruitable heroes, villians, and even some new missions.
You'll need FFX 2 and EZFX5 in order to run it.