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What is the difference between differentials and transfer cases that are used, rebuilt or remanufactured?

Used and rebuilt differentials are often pulled out of a junkyard vehicle and may or may not be of the most reliable condition. Used components can be susceptible to unexpected failure and we do not recommend them. Rebuilt differentials have been inspected and severally worn or broken parts have been replaced, but their quality can vary widely and they often lack a long-term warranty.

Remanufactured differentials and transfer cases, on the other hand, have been fully disassembled, inspected, and repaired to the same standard as a brand new part. All remanufactured parts are measured against factory standards and tolerances. With a remanufactured part, you have the peace of mind that your part is reliable and comes with a 3 year, unlimited mileage warranty.


What is the difference between a limited slip differential and a standard/open differential?

Standard/open differentials deliver power to the wheel that is experiencing the least resistance when traveling over a surface with less traction, such as an icy road or gravel. Limited slip differentials, on them other hand, send power to the wheel that is not spinning. The term PosiTraction is often substituted for limited slip differential.


How long will it take to receive my differential?

We have most popular applications in stock so we can normally ship the item within 2 days. If we have to build a differential for your particular application, we can generally have it within a week. After it leaves our facility it takes between 3-5 days.


How do I determine what my vehicle’s gear ratio is?

If you’re not sure what your gear ratio is, there are a couple of methods to determine what it is. Often, all you need is your VIN. Visit a VIN decoder like the one at and enter your VIN. If your vehicle manufacturer doesn’t include the information you need in the VIN, you can also determine the gear ratio by dividing the number of teeth on the ring gear by the number of teeth on the pinion gear. Still not sure? Just give us a call and we’ll help you figure it out!


What is a core policy?

All National Differential remanufactured differentials and transfer cases have a core charge. For your convenience, the core charge is no longer billed to you at the time of sale! Instead, you’ll have 30 days to send the old differential or transfer case back to us, which we will then inspect. If we don’t receive the core within the 30 day time period, you will be charged for the core. Cores must be received INTACT. If core is missing pieces or has been cut or broken or altered, call us to discuss options if any.

A core charge is a common method used in the auto industry to promote the recycling of old parts. This keeps costs down for everyone, makes parts more widely available, and is better for the environment.

The core that is returned to us must be a like-for-like Make, Model and Type, but not a junkyard core. Cores need to be sent back to us after being drained of all fluids and oil, assembled and attached to the same undamaged container with which your remanufactured part was shipped to you.


Do you charge for shipping?

Each differential and transfer case comes with a fixed shipping cost that includes free return shipping of the core, making it easy for you to send back your old unit and avoid being charged extra for the core. These prices are for a commercial destination only, please call for estimated costs in residential areas.


Have a question we didn’t answer? Give us a call at (719) 725-1559.