How to turn off outside speakers on a Arctic Fox 811

My outside speakers are considered the REAR speakers and the inside the front speakers so the Fader is what I use to control the outside volume. Yours should probably be hooked up that way.
I would bet that if you pull out the stereo all of the speaker wires are there, it just might be a mater of figuring out which one is which and then connecting them to the right channels.