1979 Chevy K10 - What is this electrical part?

[Steve1]

I'm restoring a 1979 Chevy K10 and have this left on the bench. It looks like it was bolted to the fire wall based on the undercoating on the clamp. Any idea what it is and where it goes?

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[Sad Sack]

Did truck have a tach option?
Looks like a tach filter. And plug end looks like it fits in the HEI coil / cap. Final answer.

 

[Edelbrock]

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Did truck have a tach option?
Looks like a tach filter. And plug end looks like it fits in the HEI coil / cap. Final answer.

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