It's on a 1996 v6, 3800 series II.

 

That's called a hose clamp!
The clamp is holding on a rubber cap, like what's used for capping off open manifold or carb. vacuum ports.

 

thanks i need to replace it but i didn't know what it was called. so it's just called a radiator hose clamp and rubber cap?

 

it looks like its just plugging that overflow port, so anything you can make a good seal with will work. if you can get a freese plug small enough that would also probably work

 

Shouldnt it be connected to an overfull hose? Or do they all get capped off?

 

the one directly above it in the pic is his overflow.


my radiator doesnt have that extra little spout on it so im assuming its some option for another vehicle which shares the radiator. I know the newer fbodies have some other cooling options on them.