They use thin scrotch type to type around the outside bearings for bevel gear(angle one). They try to eliminate the slop of the housing for that bearing.

It is very difficult to control the contraction of the plastic and graphic once they are release from the metal mold. So far, only Japan is the leader in this field. EVO 3 idea is very good. That's why SD also uses the same type of gearbox.

That's why it is not that company can do it properly. So far, Yokomo is the best. You have to round off the edges of the gearbox like any other brands shaft car.

Once you have a smooth drivetrain and you car will also be quieter too.