Picture of knock sensor on 1999 Chevy cavalier z24 of location?

I can't upload photos on this sensor, because it is very hard to see. It is located below the heater tubes that lead to the heater core. On the 99 model it is bolted into the engine block with 1 bolt going through the center of it, and the sensor is round, with a wire, and is about the size of a standard lug nut. You may need a mirror on a stick just to see it.

I would still be interested in a picture.

Thanks

go to autozone.com type in knock sensor in the product search, then year,make model. There is a photo there.