knock sensor, '93 Buick Park Avenue Ultra

I've never seen a 3.8 GM, but on my 3.1 it's on the back of the block. It has a heat shield around it to protect it from exhaust manifold heat.

Thanks for the suggestion. The first place that I looked was on the back of the block, down near the transmission, but I couldn't find it there. I checked my book, and it said it was up by the throttle control, but I can't find anything there. I checked autozone.com, and they say it's actually on the cylinder head toward the rear of the engine, but I can't find it there either. Of course, I also looked all over the engine for it. So, either I don't really know what I'm looking for, or else it's hidden pretty well. If anyone knows where that knock sensor is, I'd appreciate your help!