Find the identification record
The axle or differential may carry a tag showing model, serial and ratio information. Its location varies by assembly, so use the component service information or ask your repair shop to locate it. A truck build sheet can provide a starting point, but it may not reflect a replacement installed later. Photograph the complete tag and record all fields exactly. Include the truck VIN and note whether the axle or differential is known to have been changed.
Distinguish ratio from the assembly model
The ratio describes the relationship between input and wheel rotation, while the model identifies the assembly family. Both matter when finding a replacement. Similar housings can contain different gearing or equipment. Keep the model and serial numbers with the ratio instead of sending only a shorthand description. If you are looking at a tandem assembly, tell the specialist which position needs replacement and provide information from the relevant units.
Confirm what is actually installed
If the tag is missing, unreadable or inconsistent with the vehicle records, have a qualified technician identify the unit using appropriate service methods. Do not guess from the truck model or another vehicle in the fleet. A ratio mismatch within a driveline can have serious mechanical consequences. Physical verification may require workshop access and proper equipment, so avoid improvised checks under an unsupported truck. Send the technician’s findings with the part request.
Check the rest of the specification
Ratio is essential, but a replacement also needs the correct application and interfaces. Ask about the assembly model, axle position, connections and relevant options. State whether you need a complete axle, a carrier assembly, a differential or another component. These terms are sometimes used loosely in listings and phone conversations. Current photos and a written description help both sides quote the same scope and identify any parts that will need to be transferred.
Review condition and delivery
Request the known donor information, condition notes and inspection information for the exact stock number. Ask for photographs of identification marks and visible damage. Confirm what is included, how the part will be shipped and what equipment is needed to receive it. Before installation, have the shop compare the delivered unit with the order and the old assembly. Keep the ratio and identification record in the vehicle’s service file to make the next repair easier.
- Full axle or differential tag photo
- Installed ratio verified by your technician
- Correct assembly position, connections and included components
Every truck has its own details.
Use this guide as a starting point. Ask a qualified technician or parts specialist to verify your exact configuration before ordering or installing a replacement.
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