Fiesta 51 plate rear speaker install
 

Hi. I decided to replace the factory speakers in my 2 door 51 plate Fiesta Flight and want to put speakers in the back somewhere too, just to get a bit more depth in the sound. Having googled a bit, I've learnt that factory fitted wiring to the back is a bit hit and miss, so thought I'd come to you guys :)
My front speakers only have the white and yellow wires on them, so am wondering which wires I should be looking for, if they exist for the rear. Would they only run down the off side, rather than both sides?

Edit: I think I have a diagram for the pins now which matches continuity readings I took earlier
White/black - LF+
Yellow/black - LF-
White/red - RF+
Yellow/red - RF-
So, I assume the colours in the loom do not correspond with what goes into the unit?
https://cimg1.ibsrv.net/gimg/passion...b36e658b5a.jpg