To be certain, you should:
1. Consult your owner's manual: This is the best resource for the exact location.
2. Look at a repair manual specific to your year and model: These manuals often have detailed diagrams.
3. Search online for images: Search for "[Your Year] Ford Ranger 4.0L engine oil pressure sender location" on Google Images or a similar search engine. You'll likely find pictures showing its location.
Remember to be careful when searching for it as the engine is hot after running. Let it cool down completely before attempting to locate the sender.