This is the TSB bud.
http://www.350z-tech.com/zwiki/TSB_04-0 ... _Rear_Axle
It says for 03 cars but they dont ever seem to have sorted it. Mine clicks and its an 05.
The dealer may try the quick fix which is to grease it. It will probably come back though.
ZMANALEX sells the kit to fix it if the dealer wont do it.
The dealer charges over 1k so expect a fight.