This plate is found bolted to the transmission on all 2007+ Nissan  350Z / 370Z and 2007+ Infiniti G35 / G37 equipped with a 6-Speed manual transmission and VQ35HR or VQ37VHR powertrain. This plate is used to allow basic inspection of the clutch and flywheel assembly without the complete removal of the transmission. This plate is necessary, if left un-installed dirt and other debris can make it into the bellhousing causing damage to the clutch assembly and bellhousing.

OEM replacement Inspection Plate Bolts can be found HERE.