Xoutpost.com - Audio components in the rear

I've been searching the internet for days and haven't been able to find a picture or diagram of the rear electrical compartment (drivers side in the cargo compartment behind the access panel) There is a silver box that almost looks like a amp with a bunch of wires running into it. I'm trying to figure out if this is related to the audio system and if those wires are going to the speaker so I can splice in a RCA cable for an amp. I don't know what that compartment is called and can't find a picture with the same box. It possible I’m not using the correct terminology and that may be limiting my search. If anybody knows what that compartment is called or knows where to find a diagram labeling each specific component, it would be greatly appreciated. Thanks.