Help with engine wiring

This wiring comes out of the firewall driver's side, it is more than 5 feet long. I would assume it goes all the way to the starter solenoid???? What are the hard rubber squares (fusible links???) what is the thing at the end, does that go to the voltage regulator???? Also, where does that plug-in go to???? Sorry, I am not a electrician by trade!

The plug (I believe), is for the under hood light. I've seen a few with the lamp plugged in to that. The end goes on the left side of the starter relay.

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