That's not a factory wiring diagram. It may be correct, or it may not be.
Factory diagrams usually have the wire coded with a circuit identifier and wire gage as well as the color.
The 1967 Barracuda diagram is in the 67 Shop Manual supplement.
I think it was Alan who had this available as scan years ago. I think you can download it from the Hammtramck Historical (maybe under TSB) or maybe mymopar.
Let me see what I have that might help you through this part.
edit.
See if this helps.
Red with white trace is a feed from the main junction. It is always hot.
The second terminal on that feed is not used.
View attachment 1715267181
The black 14 gage wire is the "accessory" feed. It is hot whenever the ignition switch is in run or accessory. It looks like the second terminal to the middle should have a jumper connecting them.
