Mine accidentally this cap detached from its place when i did the maintenance in the splines.I didn't knew that you can find is as a spare part,so i tried to weld it with some epoxy ''Permatex'' high temp for metals.It worked,but i am thinking to replace it with a new one.I have never done this job and i don't know how easy is to pull out the vent cone from out and no need to open the final drive to do that job.Hope that no need to open it!
Becareful on the installation of the new one,it has a very little amount of weld and only in the centre of the cap for the reason that its housing it is very conical.
DON'T tap it AROUND of the cap but only in the CENTRE!If you tap it around you will break it from its welding for sure!
If you do that jobe before me or some other let us know how easy or difficult was...