GregTech registers its gears under both the gear and gearGt prefix. The former prefix is used by most mods, and as a result GT gears can be used in most recipes from other mods. The latter prefix is only used for GregTech gears and also used for any GregTech recipes, meaning gears from other mods cannot be used in GregTech recipes. The primary reason the gearGt prefix exists is because of how much variation there is in gear crafting recipes, meaning it is impossible to tell what materials a gear comprises just from its oredict tag.
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