Location of 2003 Chevy 5.3 liter oil pressure sending unit?

The oil pressure sending unit on a 2003 Chevy 5.3L engine is located on the passenger side (right side) of the engine block, near the front. It's usually a small, cylindrical unit with one or two wires connected to it. You'll likely find it fairly close to the oil filter.

However, the exact location can vary slightly depending on the specific engine configuration and any aftermarket modifications. A visual inspection is recommended to confirm its location. Referencing a repair manual specific to your 2003 Chevy model (and engine code, if available) would provide the most accurate and detailed information.