The Quest has been through three generations. The first was a V6 3-door minivan sold from 1993 to 1998. It was sold in Cargo, XE, and GXE trims and body types.
The second generation was sold from 1999 to 2002. The new trims were the GXE, GLE, and SE for the sport model. New luxury features on the Quest included a sunroof and 6-CD player options.
The third generation has been sold since 2004. It is longer and has more distinct styling to set it apart from the competition. It has been praised by some while mocked by others, but overall reviews are positive. The current trims are Base, S Special Edition, SL, and SE.
Sales have been declining for the Quest, but it will not be discontinued any time soon. The 4th generation Quest is the 2009 model. Production is moving back to Japan for the new Quests.
These can be found on the used minivan market. If you are wondering about buying a used Nissan Quest, your best bet is looking on eBay. You can also find parts for your older Quest on there.