Where is the crankshaft sensor located on a 1996 Buick Riviera?

The crankshaft position sensor (CKP sensor) on a 1996 Buick Riviera (assuming it has the 3.8L supercharged engine, which was common) is typically located on the passenger side of the engine block, near the bottom of the engine, close to the crankshaft pulley. It's often tucked in a somewhat difficult-to-reach location.

However, without knowing the exact engine code, this is just a general location. It's best to consult a repair manual specific to your 1996 Buick Riviera's VIN number or engine code to get the precise location. A repair manual will have diagrams and photos that will be much more helpful than a general description. You can find these manuals online or at auto parts stores.