[Serum]

Here;

Source is amainhobbies;

Perhaps there is another gear you can use, but used in savages these gears are torn apart pretty quick..

'This is a pack of replacement differential internal bevel gears for Kyosho buggies, and fits the Inferno MP7.5 and Inferno MP777 family of buggies. These are the standard internal gears for the front, center and rear differentials on Kyosho buggies, and are the most popular type of differential gears for US style tracks'