whats the size of the bolt on the rear diff to fill oil, hard left turns on 2002 Kia Sportage

ok. the rear is leaking and i just repaired it with siclicone. now i need to fill it but i dont know the size of the bolt, is it special? second i have no power steering on the left side after a long road trip, idk if its a control arm or worse

Asked by for the 2002 Kia Sportage