* Check the sticker on the driver's side doorjamb: This sticker often lists the axle ratio.
* Look at the RPO codes (Regular Production Option codes): These codes are usually found on a sticker in the glove box or under the hood. The RPO code for the axle ratio will tell you the specific ratio.
* Physically inspect the axle: This requires removing the cover of the differential and counting the teeth on the ring and pinion gears. This is the most accurate method, but it involves some mechanical work.
Without knowing your truck's specific configuration, it's impossible to say definitively what your gear ratio is.
