What is this

[86c20RN]

Hello, I have a 1986 c20 454 auto that I am looking over and don't know what this is. Obviously at this time it is just laying in my engine compartment. It is on the drivers side of engine toward the firewall.
Thanks, Cg

 

[AyWoSch Motors]

I'd want to say a temp sensor, but its not threaded. Maybe a knock sensor, not sure.
What does the bottom end look like?

 

[Scott91370]

Could you get a further back picture of it as well so we get an overall idea of where it is?

And, are the wires yellow & brown?

 

[Vbb199]

I'm guessing something emissions related