Mach 460 into my 93 coupe

I have a 93 coupe that obviously did not come with the Mach 460 system. I have purchased a head unit, all of the speakers and the rear wiring harness over the past couple of weeks. I am attempting to replace my current system with this 460. The problem is that i can not find the harness that connects the HU to the rear speaker harness and the front speakers. I'm also not sure if this is one unit or 2 separate pieces. Does anyone know where i can find this information or better yet the harness(es)?

acutually, ebay is where i've gotten all of my parts, but i've been looking for over a week now and so far nothing. thought i'd just go ahead and buy it new if i could find one.