To be certain, you should:
1. Consult a repair manual specific to your 1995 Ford Econoline's engine. This is the most reliable way to find the precise location. A Haynes or Chilton manual is a good investment.
2. Look at diagrams online. Searching for "[Your Engine Size] Ford Econoline oil pressure sending unit location" on Google Images might yield helpful pictures.
3. Visually inspect your engine. Once you locate the oil filter, the sending unit is usually fairly close by. It's a small device with a single wire connected to it. Be careful when inspecting, the engine is hot if recently run.
Remember to disconnect the negative battery terminal before working on any electrical components.