1994 and 1995
- The 1994 through 1995 Vortec V6 engines have two knock sensors. One is located on the driver's side of the engine block between the rear-most and middle cylinders. The other is on the passenger side, either on the rear of cylinder head, or on the block between the rear-most and middle cylinders.
1996 through 1999
- The single knock on the 1996 and later Vortec engines is located at the rear of the engine, below the driver's side of the distributor. It is directly behind two rigid fuel lines leading to the intake manifold.
- The knock sensors in 4.3-liter V6-powered light pickups, such as the C1500 and Silverado, are in slightly different locations than the SUV and passenger vans. The pre-1996 models have two sensors, one on each side of the block. The later year models have the single knock sensor mounted in the engine block in front of the starter.