WARNING: This page is about a different car, the 2005 Nissan Quest. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Ducts - Front Heater & Cooling Unit Assembly Components
Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Ducts - Rear Heater and Cooling Unit Assembly Replacement Components - With Torque Specifications