Radiator help!!!
 

I have a *hopefully* easy problem. I got to work the other day and noticed a trail of coolant leading to my car. No overheating or anything. Pop the hood to find something I've never seen/noticed before. What is supposed to go here and how can I plug it? I've never noticed it before but I put my finger in the hole (that's what she said) and its like there is a semicircle shaped hole like some sort of plastic plug blew halfway out.
In the picture it's the part that sticks out on the right side right between the top trans cooler hole and the clip that supports the fans.
Any and all help is appreciated. Thanks in advance.

Edited in first post

Looking Good, please share with us what vehicle this is for and I'll move it to the appropriate section. This is the INTERNAL ENGINE section.

2000 trans am sorry

Firebird section it is.

Coolant level sensor goes in there. If it came out of the radiator, you'd have a low coolant light in the cluster. It's probably hanging on it's plug.
https://cimg8.ibsrv.net/gimg/ls1tech...799ff3f62e.jpg

Strange because I don't have a coolant light or plug for that sensor nor have I ever seen one there and I've rebuilt this engine twice. So is that sensor an option for these cars? And if so is there a way to plug it? I guess I could always just buy the sensor and not plug anything into it...

All 4th gen F-bodies had this.

As you see, without it there's a hole in the radiator so it must've been there before.

I'm pretty sure I'm not crazy.
 

https://ls1tech.com/forums/generation-iii-external-engine/1747422-not-sure-what.html

This post says they were eliminated in 2000 so there must be some sort of plug for it.

gmpartsdirect.com shows it for the 2000 & 2001, part number 19299321.

What's not shown is some kind of dummy plug to go in the radiator.

if you look at the sticker on the factory air lid that refers to the coolant fill procedure it refers to the low coolant light and says V8 ONLY.

if the car started as a v6 then that could explain the lack of the sensor.

Thanks Mr. Richards, that is interesting. However, I believe the OP's car to be an original V8. Looking Good?