Hey guys, newb here. I found out that I need to replace one of the oxygen sensors on my 93 740il and decided I could do this job myself. I purchased the sensors and tool and started to do the job. However, I am unable to locate it. Where are they? I've jacked the car up and traced the pipes to no avail.

http://img.photobucket.com/albums/v247/ecangian/BMW001.jpg

http://www.realoem.com/bmw/showparts.do?model=GD83&mospid=47364&prod=19931000&btnr=18_0222&hg=18&fg=05

That helped tremendously, thank you.