Hi, I'm brand new here. I need some help. I have a 2008 XL Extracab with the low cost radio. Meaning, it has no back speakers. Fronts in the doors only. Now I took the seats out and lifted the mats to see if I could find wiring back to the rears so I could put in speakers. I did not, so I ran wire up to the front. Now, when I pop out my radio, All the wires for the rear speakers are there in the plug. Soooo, they terminate somewhere between the radio and the floor. I assume there is another wire they used to tail onto this one when they installed rears. I cannot find the end to the rear wires coming out of the plug. Any idea where they terminate so I can plug my new rear wires into them??

Thanks!