1. Check the Door Jamb Sticker (Most Reliable):
* Open the driver's side door.
* Look at the sticker on the door jamb. This sticker often lists the axle ratio (gear ratio) among other vehicle specifications. It might be listed as "Axle Ratio" or something similar.
2. Check the Build Sheet (If Available):
* If you have the original window sticker or build sheet from when you purchased the truck, it will likely list the axle ratio.
3. Look at the Casting Numbers on the Differential:
* This method requires getting under your truck. You'll need to locate the differential (the housing that contains the gears).
* Clean any dirt or grime off the differential cover. Look for casting numbers stamped into the metal. These numbers *may* indicate the gear ratio, but it's not a guaranteed method, and decoding the numbers can be tricky. You'll likely need a Dodge parts manual or online resources to interpret them.
4. Jack Up the Truck and Perform a Calculation:
* This is the most involved method and requires some tools.
* Securely jack up the rear of the truck and support it on jack stands. Safety first!
* Mark a spot on the driveshaft and a spot on the tire.
* Rotate the tire exactly one full revolution.
* Count the number of times the driveshaft rotates.
* The gear ratio is the number of driveshaft revolutions divided by the number of tire revolutions (which is one in this case). For example, if the driveshaft rotates 3.73 times, your gear ratio is 3.73. This method is less precise, and any slippage will affect accuracy.
The most reliable methods are checking the door jamb sticker or the build sheet. If you don't find it there, method 4 is the next best option, but it requires more effort and is less precise. Using the casting numbers is the least reliable method.
