Obrianmcc
Observer
So is the rear axle breather extension to keep water out?
That is one function ... I've read that rapid cooling, such as crossing a water body, can create negative pressure inside the diff drawing in contaminates through the seals (ie water). The other is to allow it to vent freely to atmosphere vs through the one way check valve that notably over time corrodes itself shut ... once this happens pressure builds inside the diff venting out the path of least resistance .... being the seals.