As for the 7.3 retrofit, is that fairly easy or takes it down for a while? Trying to keep the system "turn key" if that makes sense since others use my vehicle who while aren't dumb with vehicles, shouldn't have to engage in a lengthy ritual with the glow plugs each time they need to use it
So, lets see:
A 7.3 controller has 5 wires to be connected:
1. Power input. You might need to run a heavy 6 ga wire from the battery/fender relay terminal to the back of the motor
2. Power output. This goes to your glow plugs. You will either need to make a harness, or modify one from, say, a 6.0 motor:
https://www.amazon.com/APDTY-2004-2...&redirect=true&ref_=oh_aui_detailpage_o00_s00
All it is is a set of wires with connectors for each glow plug, connected to a post on the controller.
3. Ignition on - You just need a hot-in-start-and-run wire to power the controller/positive side of the relay; there should be one in the stock harness back there.
4. WTS light(Doesn't have to be connected, but if you want it, you'll need to connect)
5. Ground. Just a little black wire which can be connected to a nearby bolt; I used the one that holds the return rail 'clamp'.
If you get your wiring schematics out, it shouldn't be more than a couple of hours, if you are being slow about it.
late 6.9/7.3 style controller wiring:
You must be registered for see images attach
You must be registered for see images attach
So, it looks like you can pull the red/green wire from the controller plug and use that for power.
WTS light may be more of a challenge: The 6.9 light wire is pulled high to power it, the 7.3 is grounded to power it.
You can either:
1. Pull the WTS light out of the dash, find the grounded terminal, and connect it to a power source instead.
2. Invert the signal using a relay under the hood. Here's a great explanation of how the common 'bosch style' relay works:
http://6066gmcguy.com/BoschRelay.html
(basically, you'd use the 'ground to turn on circuit', but instead of using a switch, you connect that wire to the controller. The output, terminal 87, gets connected to the factory WTS light wire somewhere.
edit:
I will say that, /when working/, it's a very foolproof process: Key on, wait for WTS light to go out, crank and she fires right up. One dead glow plug, however, will make it much harder to start(more cranking), and with two dead it's even harder.