The Mustang ECU location. Right on the Fuse box (underhood) near the passenger shock tower.
Here are the unplugged connectors on the harness, NOT including the two grounds and the O2 sensor plugs.
I don't know what this is. Look it up on ALLDATA.
Same here, I don't know.
This is what I'm calling the "body plug". My 2J has something similar. This is where I'm tapping into everything that I need to tap into. ALLDATA should give you a detailed pinout of this, so you will know which wire goes to the EFI Power, etc. I believe this plugged into or near a fuse box/relay panel of some kind. That is what should be part of the "chassis harness".
These are your battery connections.
This is the main power wire feeding 12v+ to the fuse box. This is where all the power from the battery gets distributed to the rest of the vehicle, with the exception of the starter itself.