Step 1. Check you can remove and refit the filler plug BEFORE draining the old oil.
That way you know you can refill and not have an empty diff and then have the hassle of sorting out the refill.
SOD’S LAW........there’s always one bolt/screw that fails to come loose easily or snaps off.
Inaccessible fixings sometimes need “ special tools”. These might be spanners adjusted ( ground slimmer, bent to fit etc. Keep them in a special tools toolbox! Keep it a secret so you can lend them to someone who you know will return them.
