Connector C105 - What up with this?

[450slcguy]

1980 450SLC

I've been reviewing the engine wiring harness against the schematic on the 107 CD. In several spots my wiring harness insulation is starting to become brittle and cracking off.

What's troubling me is this C105 screw terminal block. It's identified as a 4 post terminal block mounted on the metal bracket supporting the coolant overflow tank. Only 2 of the 4 terminals are being used, but on the wiring schematic all 4 terminals are being used. Added to this are 1 terminal for the main battery cable and another terminal with 5 heavy gauge red wires.

Nowhere does the schematic show the 2 lug terminal block with the plastic snap down cover that's on the front passenger fender well. This is two terminal. 1 terminal is for the thick main battery cable(35ga.), and the second terminal has 5 thick red wires on it.

This is making it very difficult to trace the wires. Nothing is as it should be in this area according the the CD schematic. I'm using the correct year/model MB diagram, and have also referenced several other sources, all showing the same layout.

Anyone else run into this problem? All the wiring harness on my car is stock, nothing has been modified nor hacked. It seems to me that terminal C105 is really two different termnal blocks that the schematic incorporates into one.