While taking off my stock exhaust manifolds, I broke this sensor on accident. It is between the 1st and 2nd spark plugs on the drivers side. It screws into the head and is definitely sensing something with the coolant because I unscrewed the brass fitting that the sensor goes into and coolant came pouring out. I figured it was the water temp sensor, but according the Shoebox's website, thats the sensor on the waterpump.

All help appreciated. Thanks.

 

You are correct.
There are two temperature sensors.
One in the head and one for the waterpump.
If I remember correctly one goes to the temp gauge and the other goes to the PCM.

 

OK now i just need the part number and I'll be all set.

 

The one in the head is the guage temp sensor:
GM p/n 25037332