* Check the sticker on the driver's side doorjamb: This sticker usually details the truck's specifications, including axle ratios and options. Look for mentions of "limited slip," "LSD," or a code that indicates the presence of a limited-slip differential. This is the most reliable method.
* Look at the differential itself (requires getting under the truck): Limited-slip differentials often have identifying markings on the cover, though this isn't guaranteed. Some have a small tag or casting mark. However, this is difficult to do and requires some mechanical knowledge.
* Check the owner's manual (if available): The owner's manual should specify the axle configuration and options included with the truck.
* Run a VIN (Vehicle Identification Number) lookup: Several online services can decode your VIN and provide detailed information about your F-350's factory specifications, including the rear axle type. Be cautious of free services; some may not be accurate or reliable.
* Feel for the differential action (requires testing and mechanical understanding): This is the least reliable method. With the truck parked on a level surface, jack up one rear wheel. Rotate the wheel by hand. If the opposite wheel rotates in the same direction, it *might* indicate a limited-slip differential, but other factors can influence this test. This isn't definitive and is not a recommended method for diagnosis.
In summary: The most reliable way is checking the door jamb sticker or performing a VIN lookup. Inspecting the differential itself is possible but requires getting under the truck and familiarity with differential components. The other methods are less accurate and not recommended unless you have experience working on vehicles.
