Oil Pressure Sending Unit Location

can anyone tell me where the oil pressure sending unit is located on a 2003 Silverado with a 5.3? My oil pressure guage is not moving and I think this may be the problem........

Try looking on the backside of engine block, at top where intake manifold meets block. It will have only one wire going to it. The case of sending unit is the ground.It looks alot like the temp. sensor.