mustang 01 mach 460 h.u. change

I'm having the same problem with my 02.  The second harness your refering to should have 8 wires.  Each rear amp uses 3 wires from the head unit (+, -, and remote).  The other 2 wires appear to be unsheilded grounds which I have no idea about and do not make it to the amps.  If you look at the amps in the trunk, you'll see the 3 power wires going in and can get the colors.  I have been looking for a month and have not found a second harness for these amps!  And when I tried rigging the power leads my mids were restored, but there was ALOT of feedback and noise.  I scrapped the factory project and am rewiring the system and installing a new Kenwood 4-channel instead.

Here's what I have been able to find out about the Factory Mach 460 amps: Front amp handles all 4 2-inch tweeters, 1 rear amp handles the front 2 6x8's, and the other rear amp handles the rear 2 6x8's.  All speaker wires are run through the first amp, then redistributed to the other 2 (preamping).  The power leads for the rear amps are in the second harness.  The following sites are good starting points:  http://www.flemworld.com/95/mach.html and http://carstereohelp.com/wireharnessFord1.htm