Stereo guru's help!!

[Reecard]

I recent purchased a Avic-F700BT for my X. I went to put it in yesterday with the help of a buddy. We did not have much luck. Does anybody know how we can put a new head unit in and still use the stock amplifier? We figured out that my stock unit is just a controller and everything is in the rear. I really want to utilize the factory amp since all the crossovers for the speakers are built in. It has factory nav, DSP, and a cassette player in front, so there has to be line level signal going to the rear to the amp, but does anyone know which colored wires they are? Or does anybody, I mean anybody, make a wiring harness for these vehicles? Or are we going to have to splice into the wires that we need? We were able to get the unit powered up but we could not figure out what line level wires to use, if anyone can shed some light on this that would be great.

Thanks in advance.
Todder