* Check the sticker: Look for a sticker on the driver's side doorjamb or glove compartment. This sticker usually lists various specifications about your truck, including the axle ratio.
* Look at the axle tag: The axle itself usually has a tag stamped or affixed to it. This tag will indicate the ratio. You'll need to get under the truck to see this. The location varies slightly by year and model. It's usually on the differential housing.
* Look up your VIN: Using your Vehicle Identification Number (VIN), you can often find the axle ratio online through various sources, including the manufacturer's website (though this may require some digging) or third-party vehicle history websites.
* Manual Calculation (least reliable): This method requires jacking up the rear end, marking a point on the driveshaft, and then rotating the driveshaft one full revolution. Count how many times the tire rotates. The ratio is the number of driveshaft revolutions divided by the number of tire revolutions. This method is prone to error and isn't recommended unless you have no other options.
The sticker and the axle tag are the most reliable methods. Start with those. If they're missing or unreadable, then try looking up your VIN. Avoid the manual calculation unless absolutely necessary.
