Then it sounds like the NSS is your problem. You can check continuity across pin 5 and pin 6 on the NSS connector (not the wire harness side). Pin 5 and pin 6 should be connected when the shifter is in park or neutral.
Where is the rest of the black/white wire in your picture? Looks like it is missing/cut.
Edit - could just be the picture, maybe it is going behind the orange wire.
You can't test for power at pin 5 of the NSS that way. Pin 5 gets its power from pin 6 through the NSS so the connector would need to be hooked up. You only get power to pin 5 if the shifter is in neutral or park, that is what prevents you from starting in gear. However, if you don't have power...
Do you have power at pin 6 of the NSS connector with key to start? How did you check for power?
How did you check for power at pin 5 of the NSS connector?
Is the NSS connector part of the engine harness you replaced?
I was looking back at this because I thought you checked pin 5 on the NSS but you did check pin 6.
This means:
You checked for power incorrectly at pin 6 of the NSS connector. Did you check on the NSS or the connector going to the NSS? You should unplug the connector and check for power at the...
If it were me I'd keep working down the circuit. At this point I'd probably pull the connector on the starter and check for 12V at the starter with key to start. If you have 12V there then your starter is probably bad, as has been suggested by a couple people. If you don't then you are back to...
The chart you posted shows where each source gets its power. All of the sources you are asking about get their power from FL AM1 - AM1. The path to each source is separate. You've already confirmed power to AM1.
This snip from the Power Source page shows AM1 goes to the ignition switch and then...
This is fun, which probably says something about me if I think looking through wire diagrams is fun.
Reverse lights go through IH1.
Gear indicator lights get power from the NSS which gets it's power through IH1.
A/T light gets power from IH1
Oil light I can't tell for sure because I'm not smart...
I was betting on the fusible link. If you are getting power to the AM1 fuse then the link is good. Did you check continuity on the AM1 fuse to make sure it is good?
To be clear, when you turn the key to start the truck you get nothing - right? No starter turning? I mean, this makes sense if you...
You can check continuity across the fusible link to see if it is good. Some have suggested this may not be reliable with the links but I don't know about that. It's pretty easy to check continuity.
You could also pull the AM1 fuse and check continuity across the pins to verify it is good.
You...
Is the starter turning? If not then you are still troubleshooting the starting circuit. Did you happen to check for 12V at pin 6 of the NSS connector with key to start while you had it disconnected?
Here is the entire starting circuit. If the starter isn't turning then your problem should be here.
Battery
FL AM1
Junction block
AM1
EA2 connector
Ignition switch
I13 splice
IH1 connector
Neutral safety switch
E19 splice
Starter
My guess is you aren't getting 12V to starter at pin B. You just...