Where is the oil sending unit on a Chevy G20 van 1997 5.7?

The oil pressure sending unit on a 1997 Chevy G20 van with a 5.7L engine (likely a Vortec 350) is located on the passenger side of the engine block, near the front of the engine. It's usually a relatively small unit with one or two wires connected to it. It's often near, but not directly on, the oil filter.

Because of the variations in engine placement and accessories, you'll need to visually inspect the engine to be certain. Look for a small sensor with a wire connector near the oil filter and on the passenger side of the engine. A picture online showing the location on a similar engine would be helpful if you have trouble locating it.