I've also had a leak which coincided with my front propshaft/differential 'enhancement' and I'm wondering if mine has the same problem.
Back in May 2007 there was a bulletin that covered this. With reference to the diagram below, the straight edge on the differential breather adapter must be facing forwards towards the front of the vehicle.
The bulletin advises that the breather pipe adapter cannot be reorientated in the differential housing without damaging the housing and therefore the complete differential must be replaced!