Where is the knock sensor?

Hey guys, I finally put my Saturn up on a diagnostics device and it gave me 4 errors retaining to the EGR valve and the knock sensor. The car is a 1998 Saturn SL1 with a manual transmission. Tomorrow I'll be going to the local junkyard to pick these two parts up for cheap (Saturn retails them pretty expensive). I did some light research but I can't seem to find where the knock sensor is, could anyone show me some pictures or lead me to it? Thanks :)

I'm not 100% sure but I think its on the back side of the engine, firewall side. Might be easiest to put the car up on ramps and go at it from the underside.

http://img.photobucket.com/albums/v107/federal_rider12/car/S4020202.jpg

right next to that brass cylinder (my aftermarket oil pressure sender) is the knock sensor. your factory oil pressure sensor wont look anything like my sender there, it will look like a normal sensor with 2 wires down to it.