Not sure how different the ls3 is, but I’m running a 98 Camaro temp sensor, two wires for the pcm and one wired directly to my stock gauge.
ACDelco 12551708 GM Original Equipment Engine Coolant Temperature Sensor
https://www.amazon.com/dp/B005OVAUN2/
Edit: are you looking for an air temp sensor? In that case, I totally misunderstood. Sorry.