On a 1998 Ford Mountaineer V8 (4.0L or 4.6L), the spark plugs are located on
the top of the engine, under the valve covers. You'll need to remove the valve covers to access them. There are eight, one for each cylinder. Their exact position relative to each other will depend on the specific engine (4.0L or 4.6L), but they'll be arranged in a configuration to match the V8 cylinder layout.
Important Note: Accessing the spark plugs requires some mechanical aptitude. If you're not comfortable working on your engine, it's best to take it to a qualified mechanic. Improperly installing spark plugs can damage your engine.
