go underneath & look towards the back,behind the Gbox drain plug where the Gbox matesto the Tbox there is a circle,& if you were paying atention when u had the Tbox of theres a drain channel down from where the seal on the main shaft is,if u nick the seal it leaks down there & onto the floor,when you bolt them together its a good idea to put a dod of sealer in the channel so if it starts to leak it will contain the oil,
not the right way but it works