[JL8Jeff]

That's strange. What was the code being set, it might be saying the knock sensor is going bad or not sending a valid signal vs giving false knock readings. I could see how a poly mount might cause the LT1 knock sensor to pick up more false knock but not the LS1. Is there any chance you pinched some wiring when doing the clutch? I thought the knock sensor wiring came out around the back of the engine.