Courtesy refers and Nissan North America refers to the part as a "Cover-Engine Under". The nomenclature used by Nissan sounds like broken english in most cases.
We sell the same part through our website as well. The best OEM parts resource for finding part numbers and OEM MSRP prices for Nissan parts is:
Nissan eStore
That is a good starting point to get OEM Nissan part numbers or to get a baseline for pricing...to keep the dealerships honest. It will also make it much easier for sponsoring vendors like us to get you a quote much more quickly.