The way I read it is the boss should point to the drivers side of the vehicle.ie if Left hand steering the boss should be pointing to the left . The illustration in the manual shows Right Hand steering fitting with the a note to say LH steering is symmetrically opposite . The orientation is to make sure one can access the filler, after installation, either a plug which is in the side of this boss or the fixing at the top adjacent to the boss . Often in practise no one checks the levels so the orientation if wrong, goes unnoticed.