Not that this is actually an help..........
Having previously replied to a couple of threads re: JDM radios, I have a feeling you are actually missing an extension lead rather than having to remove one.
From this thread
The standard radio/cd changer in my 2006 Forester has a persistant fault (error 99) on the CD player, and as I like MiniDiscs (hey, I'm getting old, I'm allowed to be old-fashioned!) I found and bought a JDM Subaru factory-fitted radio/CD/MD in double-DIN. Since Japan uses a different band of...
www.subaruforester.org
and these pics
It can be seen that the standard JDM Clarion radio fitted to the later JDM SG Foresters including Cross sports (86201SA260) has a 3.3/3.2.3 pin layout main socket which is the standard Subaru layout for early models.
The parts database shows (below) a connection lead as a separate item which I would assume is the "missing link"
The cable highlighted above is p/n 86325SA060 - unfortunately Amayama/Megazip lists it as permanently out of stock.