Having owned now 3 vehicles with this transfer case , I can say they all had/have an unusually large amount of play in the front shaft.(sometimes the flange can be loose check it).
Never seen one leak oil or cause a vibration,,when they do I'll worry about how much play they have otherwise I say it's normal. Blkknight wrote a post a while back with the actual play measurement and it sounds like heaps but it's a very short shaft. Any vibration in that area would be drive shaft related in particular the uni on the outside (front) of the DC joint. I've seen one fail with just that uni (non greasable original) destroy itself the other uni closest to the flange and the centre bearing were fine. Something to do with the way the DC joint works.

BIG O
03 D2 TD5 AUTO
99 D2 TD5 AUTO ACE
94 D1 TDI 3 DOOR (GONE)