Might be. Otherwise spec-r don't have to make a new gearbox la. Gear diff is relatively bigger than ball diff. Buy of course if Tamiya announce this is an official hop up option for ff03, they would make it either fitting the original gearbox, or produce a new gearbox like spec-r did. Btw, some Ching said the gas car NT1, got gear diff metal bevel gears compatible to spec-r's gear diff, is that true?