no issue at all with the build of the gear diff everything fits perfect
no issues on leaking as well as i used a tiny amount of black grease only
took about 2 full lipos just running steady laps to loosen right up and is now the best its ever felt , very happy with
yes i run on dusty tracks as well a gear diff is a good item for these conditions IMO
plus as i said i cant build a ball diff to save myself