Breathers Diff/Transfer/Gearbox

I own a 2013 Navara D40 Manual, I recently had the car on the hoist to install a rear diff breather, I checked the front diff and that had a barb welded to it. It also had a hose leading up just behind the airbox so I didn't bother changing that. when I checked the transfer case and gearbox it felt like it also had hoses on it so my question is does anyone know if that is correct and where the hoses lead up to? A friend of mine "exact same vehicle" had ARB install breathers and they told him not to worry about transfer/gearbox because they already had breathers from factory...

The three from the gear box terminate up the top of the bell housing, I'm currently getting some kits together with 5 breather ports for the D40 which extend the hoses

Thank you