Where is the oil sending unit 1987 cadillac deville?

The oil pressure sending unit on a 1987 Cadillac DeVille is located on the engine block, near the oil filter. It's usually a small, cylindrical unit with a single wire connected to it. However, the exact location can vary slightly depending on the engine (4.1L or 4.5L V8). You'll likely need to consult a repair manual or a diagram specific to your engine for pinpoint accuracy. A visual inspection with the oil filter area as a starting point is the best approach.