knock sensor location

I had a Allegro Gas Unit with a Chevy 8.1L..they were 2 located on each side of the engine block...very easy to get to and change out. Ordered them through Amazon, very inexpensive but make sure you get the wiring harness with it because that was my problem. Noise Sensors were OK but changed them anyway.
I was concerned at first on the info I received that they were located under the intake manifold which would put you spending more money if that is your case.
Hope this helps you!