The 3.5 litre V6 engine in a 2004 Nissan Quest has a timing CHAIN
It has a cam chain.
It has a chain that requires no maintenance.
2004 Nissan sentra with a 1.8L engine has a timing chain and you do not replace it.
The 3.5 liter V6 engine in a 2004 Nissan 350Z has a timing CHAIN
Yes , it must have a timing CHAIN ( the Gates website does not list a timing belt for the 2004 Nissan Xterra 2.4 liter )