Where is the oil sending unit on a 5.7 liter 1997 Chevy vortec engine?

The oil pressure sending unit on a 1997 Chevy 5.7L Vortec engine is located on the driver's side (left) of the engine block, near the front. It's a relatively small unit and often has a single wire connected to it. You'll likely find it near the oil filter, but not directly on top of it. Be aware that some vehicles might have multiple sensors in that area; one is for the oil pressure gauge and may be a different one than a sensor used for the oil pressure switch in the computer system.