Need help with the final frontier...

I think I have my electrical pretty well sorted. It's my 1974 Dodge Power Wagon. I'm putting in a total aftermarket 20 circuit hot rod kit for the wiring. Pretty well labeled plenty of wire but just a couple things that are not addressed...
Mainly the three prong transmission wires relating to the starter solenoid and the backup lights.Screenshot_20220104-161143.png
To where I have it understood in my head is the red wire is the battery and battery powered for my fuse box with a fuse link. The small black wire indicated in the picture here goes down to the starter. The yellow wire coming in is the one that when I turn it to start gets juice and the brown wire to the bottom right is the one coming from the center of the three transmission wires that's actually a ground that allows that start electricity to go through when it's in park or neutral? And the two wires on the outside of the transmission prong one going in with constant juice when the key is in the run position and the other coming out with juice to the backup lights which is connected when in reverse?....
This seems to be my last hurdle for getting all this 100% figured out...
Thank you for everyone's experience and knowledge...