WARNING: This page is about a different car, the 2006 Nissan Quest. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Front Ducts And Grilles Components
Courtesy of NISSAN MOTOR CO., U.S.A.
Ducts - Rear Heater and Cooling Unit Assembly
Fig 2: Identifying Rear Ducts And Grilles Components