The crankshaft position sensor (CKP sensor) on a 1997 Dodge Ram 1500 van with a 3.9L engine is located on the
passenger side of the engine block, near the bellhousing. It's usually mounted to the engine block itself, fairly close to where the transmission bolts up. You'll likely need to get under the van to see it clearly. It's a relatively small sensor with one or two wires connected to it.
Keep in mind that the exact location might vary slightly depending on specific modifications or quirks of that particular vehicle. A repair manual specific to your year and engine would be the most definitive source.
