axle breathers

On my front axle (1st pic), it looks pretty obvious what I need to do to replace the breather. I have just unscrewed the old breather, and can screw the new one in.

This is what I have on my back axle (2nd pic). I can’t work out whether this is a left over from an old breather that has broken off nor not? If so, do I drill it out, do I take a stud remove to it?

Looks broken off, if I remember correctly the axle casing is drilled with a thread cut into it.

Yes axle tapped, Does new breather screw into that, perhaps something like a nutsert if old thread was damaged , I would try some different bolts in it see what thread it is before removing , it might tap round with a sharp chisel on the edge

2nd pic looks like it has a thread inside it.

J

And a copper washer below should come out easy