Where is the oil pressure sending unit on located Ford e150 v8 - 5.8?

What is your question?

I need to replace the oil pressure sending unit (or sensor) on my 1993 Ford e150 v8. The oil gauge has been flickering back and forth to normal to low. Now its stuck on low no matter how long the engine runs. Can you also provide me with the following information including special tools or precautions to take before installing a new one.