65amp wiring/trouble shooting

Three connectors and heavy wiring. Likely a heavy duty system. Lets figure it out.
Begining at the battery. Red wire (A1) goes to the starter relay shown here.

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We see a junction here with two other wires. One large red wire and the other a black? fusible link.

Next.
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Not what we are seeing here a the grommet - Other than its probably to the ammeter. Will come back to this.
We also see a red wire to a connector possibly going to the multiconnector.
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Looking at this one we see another red wire and connector that may be going into the multiconnector.

Do you have a picture of the original voltage regulator and connections?

Let me get my dinner cooking and will come back in bit.