* The sticker on the driver's side doorjamb: This often lists the axle ratio.
* The owner's manual: This should specify the axle ratio.
* The build sheet (if you have it): This document details the specifications of your truck.
* The vehicle identification number (VIN): A dealer or mechanic can use the VIN to look up the specifications.
* The differential tag: This tag is usually located on the differential itself and will show the ratio (e.g., 3.73, 4.10). You will need to get underneath the truck to see this.
Common axle ratios for the 2006 Ram 2500 4x4 included 3.73, 4.10, and possibly others depending on the options.
