What is the model number for the large blank filler panel for the 8164 mainframe?

The large filler panel for the bottom of the 8164 mainframe has an Keysight Technologies model number: 81645A. The 8164 mainframe does NOT ship with this filler panel. Consequently, if you are not using one of the large slot tunable lasers 81680A / 640A / 682A / 642A / 480A it is recommended that you order this filler panel.