4th gear on my 4x4 sounds rather noisy when I trundle around in traffic at around 20mph, though only really noticeable if I have the window down.
In addition, rapid gear changes from 3rd to 4th at fairly high revs can beat synchromesh on the 4th gear so that the gear engages with a bit of a crunch.
I suspect this is a design fault or maybe due to the type of gear oil which is different for the 4x4 than boxes of other models.
Anyone else noticed this on a 4x4?

This might sound silly but why would you be trundling around in 4th gear at 20mph. That's only going to labour the car.
As to changing at speed I have had no problems with syncro on mine, so doubt it's a design fault.

Did you get your gear box fault sorted?

No, just live with it. To be honest, I don't like dealers taking major units apart on my car unless they really have to because sometimes it can just make things worse or other faults develop.