To find the gear ratio, you need to check one or more of the following:
* The data plate on the truck: Look for a data plate, often located on the driver's side doorjamb or under the hood. This plate sometimes lists the axle ratio. However, it might not always be completely detailed, It may just list the rear axle type or code which you'll then need to look up.
* The owner's manual: If you have the original owner's manual for the truck, it might specify the gear ratios for the transmission and axle.
* The truck's build sheet (if available): A build sheet from the factory would definitively state the axle ratio. These are sometimes available from International Truck archives (if they still exist) but are rare to find.
* The transmission and axle tags: These tags may have the ratio number stamped onto them, often located on the transmission itself and the differential housing of the rear axle. You might need to look closely and possibly use a flashlight and a mirror for better visibility. The codes may require cross referencing to a parts manual or International's specifications.
* Inspect the differential: This is more of a last resort, and requires expertise. It involves counting the number of teeth on the ring gear and pinion gear, but requires removal of the differential cover. This is a mechanical process best done by a qualified mechanic.
* International Truck parts or service department: Providing your VIN to an International Truck dealership or authorized service center will allow them to access records (if available) and potentially determine the original specifications, including the axle ratio. This is probably the most reliable method if the other options fail.
In short, a physical inspection of the truck itself or contacting International is necessary to confirm the gear ratio. The VIN alone is insufficient.
