usually the 8pin only has 2 rcas, 2 amp turn ons and 2 amp grounds, Ive never seen anything like the 4 rca before and therefor it apeared to be for aftermarket 4ch- amp, sorry if i gave bad info

 

you are correct that I also have not seen this hrns with 2 rca's on it either. If I had not made the same thing and been installing stereos for over 10 yrs I might have assumed the same thing.

Thinking about it last night this hrns would drive then entire system although it would be at a low volume. Using that hrns was why I added the line driver. If you disconnect the hrns that I point to on page 2 of my sig, then it will only drive the subs.

 

this should work from http://www.crutchfield.com

Factory System Integration Adapter 1988-up Ford/Lincoln/Mercury/Mazda/Nissan Item #142C4FDK5



The Scosche OEM Amplifier Adapter is a passive electronic interface package that allows you to integrate a high-powered aftermarket receiver into select 1988-up Ford, Lincoln, Mercury, Mazda, and Nissan vehicles with premium factory systems. The package includes the OEA-4 adapter and a Ford-specific harness. The OEA-4 unit has output-level gain controls for each of its four channels which can be adjusted to properly match the new receiver to the factory amplifier. Note: If you haven't already, please enter your vehicle information or call a Sales Advisor at 1-888-955-6000 to find out if this adapter is compatible with your vehicle. Details: [ul][*]4 speaker-level inputs[*]output level adjustments for all four channels[*]works best with high-powered aftermarket receivers[*]dimensions: 3-15/16"W x 15/16"H x 2-1/16"D[*]1-year warranty [/ul]