I am in the process of replaceing my radiator and I just noticed a problem. The old one has a sensor about half way down on the back side of the passenger side. The new one looks idential except for this sensor. All the other oil cooling lines inlet and outlets and such look identical. What is this sensor and did I end up with the wrong rad?

PS: I can get pics if needed...

That makes sense, I went back out and looked and there wasn't a sensor in the coolant reserve like I thought there was. I got the part thru GMPartsDirect so I'll have to look into the policy on exchanges and returns.

Also, what lines are what as far as the other connections to the rad? There are two more on each side. I figure it is best to know what they are before I disconnect them.