Oil breather on diff

[pilotprice]

Hi
I have a 2010 roadsport 125, the rear diff spits oil everywhere on normal driving I've narrowed it down to either the oil breather or the offside oil seal

Car has a open diff (ford unit)

Currently the diff vent just has a brass 90' below with no pipe or vent? What should be fitted over the brass fitting? Does anyone fit a mesh breather filter or just a piece of pipe?