WARNING: This page is about a different car, the 2013 Nissan Armada. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Ducts Components (Front Heater And Cooling Unit Assembly)
Courtesy of NISSAN NORTH AMERICA, INC.
Fig 2: Ducts Replacement Components With Torque Specifications (Rear Heater And Cooling Unit Assembly)