What is this supposed to connect to?

[SewardsFolly]

I have these two cables in the engine bay of my 76 k10 with 350 auto and they are coming from driver side firewall. Other photos of the interior cab side. I can’t figure out from the manuals or wiring map what it is supposed to go to - anyone able to tell me?

Cheers

Copy of 76 wiring map attached too

 

[legopnuematic]

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[SewardsFolly]

Thank you very much!