To be absolutely certain, you should:
* Consult your owner's manual: This is the best resource for precise location information.
* Use a repair manual: A Haynes or Chilton manual for your specific year and model E-350 will have detailed diagrams and instructions.
* Search online: A Google image search for "1992 Ford E350 starter motor location" may reveal photos of the starter on similar vehicles.
Be cautious when looking for the starter; it's located in a relatively tight space, and you'll be working near hot engine components. If you're not comfortable working on your own vehicle, it's best to have a mechanic locate and/or replace it.