Hey, I knew if I searched enough there surely has to be a forum dedicated to something like this.
Anyways, I drive a '96 Olds Cutlass Supreme 3.1L with 175k on it. I was wanting to know where I could find the PCV valve and O2 sensor on it. I believe they are in the rear of the engine, but its so cramped in there I can't really see anything.

Here is the PCV valve location.

http://files.automotiveforums.com/uploads/779171pcv.jpg

Here is where the O2 sensor is.
There is actually one in the passenger side exhaust manifold and one in the exhuast pipe POST cat convertor.

http://files.automotiveforums.com/uploads/53201402.jpg

Hope this answers your question.

Note the pcv valve and O2 sensor illustration I have taged the chart number with a blue box identifying them.