Your best bets for finding the diagram are:
1. Your Owner's Manual: This is the most reliable source. The manual should have a detailed diagram showing the fuse box(es) location(s) and fuse layouts.
2. Online Ford Resources: Search online for "1996 Ford Mustang fuse box diagram" along with "coupe" or "convertible" (whichever applies to your car). Some forums dedicated to Ford Mustangs or automotive repair might have user-uploaded diagrams, but always verify their accuracy. Be wary of generic diagrams – they might not match your specific vehicle perfectly.
3. Repair Manuals: A Haynes or Chilton repair manual specific to your 1996 Ford Mustang will contain detailed diagrams and explanations of the fuse box(es).
4. Your Local Auto Parts Store: Stores like AutoZone, Advance Auto Parts, or NAPA often have access to repair information, including fuse box diagrams. You may need your VIN (Vehicle Identification Number) for them to get the most accurate information.
Important Note: Before working with any electrical system, disconnect the negative (-) battery terminal to prevent accidental shorts or damage. If you are unsure about working on your vehicle's electrical system, it's always best to consult a qualified mechanic.