[GTOJOE]

that sounds about right. There are 2 sensors o nthe exhaust on a GTO. One O2 sensor and one exhaust temp sensor. The exhaust temp is the one closest to the rear of the car.

 

[GTOJOE]

I believe from under the car. It should go through a hole in the floor I think. You might need to pull some of the carpet back. I can't remember 100%

 

[GTOJOE]

look under the car first. Will make it easier to locate.

 

[GTOJOE]

only reason to disconnect the o2 is if your runing a stand alone that does not require o2. SAFC-II would not effect the 02 sensor as it is a piggyback and the car still runs the stock computer. Does the car run fine? why were you looking to replace it in the first place?