How do you properly put on the coolant level sensor onto the top-passenger side of the radiator- facing the engine?

I thought I could just pop it back on, which lasted about 320 miles, until it popped off today and left a large puddle of coolant in a parking lot.

Is there some kind of sealant that should be used?

 

No sealant. A metal wire clip holds it in. The clip doesnt show up well in the picture, but it is there.

 

Thanks, I just saw that on shoebox's website.

I hope GM will let me order just that part on Monday, because I can't find it at my house.