I have this car but its still new , have yet to drive it or mess with the diffs .. Im sure you could look up specs somwhere about it .. Are you asking about the internal gears themselves or the diff housing . Im guessing your asking about the gears . I would think they are steel but not hardened. ill look around . I am almost sure they would be the same at inferno gt1 diffs also .
edit .. after a quick google search , so far I found that the shafts that hold the spider gears are hardened steel painted black and painted black .
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