That sticker on your truck’s doorjamb offers great information about your vehicle, including the VIN and barcode, the trim package, and the axle differential and ratio. An H9 Ford axle code means your truck has a limited-slip differential with a 3.55 ratio.
According to the manufacturer, you should change your differential oil every 30,000 to 50,000 miles. Low differential oil can weaken the gears and lead to failure, so it’s important to stay on top of your routine maintenance.
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