Copy the 321.cab into 318 panel folder & use this panel.cfg:

// A320 panel version 2.2
// by Eric Marciano
// (generic version)
// Modified for use with the "Aerodesigns A318"
[Window Titles]
Window00=Main Panel
Window01=Radio Panel
Window02=GPS
Window03=Throttle Panel
Window04=Overhead Panel
Window05=Gear Panel
Window06=Clock
Window07=Glass Panel
Window08=PFD
Window09=MFD
Window10=Primary ECAMS
Window11=Secondary ECAMS
Window12=Mini Panel
//--------------------------------------------------------
[Window00]
file_1024=airbus_a321_panel_background.bmp
file_1024_night=airbus_a321_panel_background_night.bmp
size_mm=1024
position=7
visible=1
ident=MAIN_PANEL
gauge00=Airbus_A321!altimeter_backup,