Use a Cessna 172 nav radio.
Go to FSX/SimObjects/Airplanes/FA-18/panel/panel.cfg
Window04=Radio Stack
[Window04]
BACKGROUND_COLOR=2,2,2
size_mm=156,308
position=8
visible=0
ident=RADIO_STACK_PANEL
zorder=3
gauge00=Bendix_King_Radio!Bendix-King Radio Audio, 0, 0,156,31
gauge01=Bendix_King_Radio!Bendix-King Radio Nav-Comm 1, 0, 29,156,59
gauge02=Bendix_King_Radio!Bendix-King Radio Nav-Comm 2, 0, 86,156,59
gauge03=Bendix_King_Radio!Bendix-King Radio ADF, 0,142,156,41
gauge04=Bendix_King_Radio!Bendix-King Radio DME, 0,180,156,41
gauge05=Bendix_King_Radio!Bendix-King Radio Xpndr, 0,217,156,49
gauge06=Bendix_King_Radio!Bendix-King Radio AP, 0,262,156,48
windowsize_ratio=1.000
window_pos=0.756,0.358
window_size=0.243,0.641
If you need help adding these, post here.