Help Identifying Un-used harness

[jrhope]

Bare with me, I'm a rookie member. I have a new to me 85 C10. While trying to troubleshoot a non-working oil pressure gauge, I ran across another harness that is not in use. I believe it is the old ESC harness. All of the emissions components on the truck were removed by the previous owner(s). I also believe it has been motor swapped, potentially more than once. It is a basic carbureted SBC with performer aluminum intake and exhaust headers. No cats, smog pump, egr, etc. All of the vacuum operated parts have been removed as well. Only have manifold vacuum to brake booster, trans modulator, and PCV. Distributor advance is connected to timed port on the carburetor. Am I correct in that the pictured harness was once ESC? Can I assume that nothing else runs in the harness and remove it and plug the hole in the firewall?

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[nvrenuf]

The second pic with the single pin connector looks like a knock sensor plug.

 

[jrhope]

You're right! A quick search turns up the same connector for a 85 C10. A little more searching suggests the other connector was the power to the ignition coil. The 4 wire connector was the distributor connector. All of this has been abandoned and I have a early style HEI dist. Thanks for the tip! I also found the old ESC tucked up under the dash. I had no idea it was there.