Hi guys and gals:
New to the forum and just wanted to jump in on the replacement of speakers. I have a 2011 SMS with Nav shaker 500. I changed out the front and rear speakers with Infinity REF6832CF up front and Rockford Fosgate R168X2 in the rear. Used the Metra 72-5600 harnesses and they are indeed reversed polarity. SO...I pulled the doors apart again and found that with a large paper clip bent streight, I could push the black and white wired pins out of their sockets. They are only held in by tension, not a clip so I simply pushed (hard) them out and carefully swapped them around so the black wire is now on top (or away from the clip side). They worked perfectly without cutting wires/splicing wires or putting new end plugs on them so they look just like the one's from Crutchfield. Now SOME older mustangs do have the harness attached to the speakers going the way Metra has it set up but the newer mustangs it is not. A quick look in the trunk at the exposed speakers will let you know which ones you need to buy. If you are looking at the speaker face down on a table with the posts turned to 6 o clock, the RIGHT one is the positive. Always! It then attaches to the bigger end plug of the Metra harness. So look at your speaker connection and see which set up you need. Again it took me 1 minute to change the wires on both harnesses (after I figured it out) so buy the cheapest ones and fix as needed!! Hope this helps. All four speakers are 6 x 8 / 5x 7 size.