This is info from Dan's link
Variable Line Level Preamp Outputs From ACM (Factory Radio) For Amplifier Upgrades
NAV IS RETAINED
These are on the Sony DSP Harness (Twisted Pair CAT5, should be easy to spot):
Front Left: Yellow (+), Blue (-) (Sony DSP: 7, 17)
Front Right: Violet (+), Brown/Yellow (-) (Sony DSP: 9, 19)
Rear Left: Orange (+), White (-) (Sony DSP: 2, 12)
Rear Right: Green (+), Gray (-) (Sony DSP: 4, 14)
Amp Remote Turn On: Red (Sony DSP - Pin 3)
Note: this remote turn on wire is NOT 12 volts (approx 6 volts)... some amplifiers may require a 12 volt input and may need to convert this output with a third party device. Some sound processors, such as the JBL MS-8, support 4 Volts and higher as a remote turn on voltage so this is not an issue.
UPDATE:
Better remote turn on wire for Push to Start Vehicles:
Connector C3501 - Pin 5 - Brown/Yellow (22 Gauge) - 12 Volt w/ Delayed Accessory Feature
- This wire is going into the 150 Watt AC/DC Power Inverter
For Vehicles With Factory Sony DSP/Amplifier Only:
Needed Wiring Terminal Inserts: Order from FordParts.com, local dealer, etc...
Part Number: DU2Z-14474-CA
I added and soldered two wires to the ACM and APIM Harnesses... These two mono out wires are required if you are disconnecting the Sony Amplifier, previously in use, to use your own amplifiers to the speakers/subwoofer without a Line Output Converter. These two wires reroute the Sync Voice from the APIM, back into the ACM, and out your aftermarket speakers.
Without adding these two wires, there will be no voice on navigation directions and voice commands will not have any feedback to confirm prompts.
It is accomplished by adding two wire terminals to the ACM Harness (Pins 8,21) and soldering them to the Sync wires on the APIM Harness (Pins 3,4).
---------- Post added at 11:39 PM ---------- Previous post was at 11:34 PM ----------
I'm kinda like you here... I'm reading this and my interest is generated.... but without a step by step how-to of someone who did it...
Removing the clipping to a flat unadulterated signal that can be amplified is obviously the best way to go, but i need my nav to work and see this proof of concept in action.
what I am hoping for honestly.... is an aftermarket head unit that retains the stock features and has a quality head unit. alpine does these quite a bit albeit expensive...
You could not do a after market. you would lose too much control of the truck. I have had plenty of people with brand new Kenwoods / alpine. and they all said they wish their HU worked as nice as mine.