How do I know what rear differential is in my Ford Ranger?

In most Ford Rangers, the rear differential is identified by the axle size and gear ratio listed on the factory data plate or through VIN decoding. The most common size is the 8.8-inch axle, with some configurations using a 9.75-inch unit. Exact specs vary by year, trim, and market, so verify using official sources or by inspecting the axle tag and cover.

This guide explains practical ways to determine your Ranger’s rear differential type and ratio, using on-vehicle markings, official documentation, and careful inspection. It will help you identify the axle size, the gear ratio, and whether you have an open differential, a limited-slip unit, or a locking differential.

Check official documentation and on-vehicle markings

Rely on factory-provided data when possible. Start with the easiest, most reliable sources before disassembling anything.

1. Door-jamb axle sticker: On most Rangers, inspect the driver-side door frame for an "Axle" or "Rear Axle Ratio" entry (for example "3.73" or "4.10"). If the ratio isn’t numeric, note the axle code for later decoding.


2. VIN-based decode: Use Ford’s official owner portal or a trusted VIN decoder. Enter the VIN and locate the "Rear Axle" or "Axle Ratio" details; if your portal version doesn’t show it, request the data from a Ford dealer using the VIN.


3. Differential housing tag or cover stamp: Some models carry a tag or stamping on the axle housing or differential cover with model numbers or size indicators (for example references to 8.8" or 9.75" ring gear). Record any letters, numbers, or codes you find for cross-checking.


4. Service history or owner materials: If you have maintenance records or the owner’s manual, look for notes about the axle type or gear ratio. Dealerships often record this information when the vehicle is serviced.

These sources provide a reliable baseline for your Ranger’s rear differential and help avoid guessing from appearance alone.

Physically identify the diff type and LSD status

A hands-on check can reveal the differential type and whether it has limited-slip or locking capabilities, which matters for parts compatibility and maintenance.

1. Inspect the differential cover and housing for identification: Look for a size stamp (such as 8.8" or 9.75") on the cover or housing, or a model code stamped into the iron. If present, this is a strong indicator of the axle size.


2. Look for an LSD/locking indicator: Some axles carry a tag or engraving that says "LSD," "Posi," or similar terms indicating a limited-slip unit. If there is no such tag, the unit is often open, unless it has a factory locker (rare on most Rangers).


3. Perform a cautious functional check (safely): With the vehicle on the ground and in a safe position, gently rotate one rear wheel by hand (or have a helper assist). If the other rear wheel turns in the opposite direction with little resistance, you likely have an open differential. If both wheels turn together or you feel clutch or carrier resistance, you may have LSD or a locker. Do not attempt high-force testing and ensure the vehicle is secure and in park/neutral as appropriate.

These practical checks help you confirm the differential type without needing factory paperwork, though they are supplementary to official data.

Use VIN-specific resources and dealer help

If you want the exact specification for your exact vehicle, VIN-based resources provided by Ford or your dealer will give you the precise axle ratio, model code, and LSD option for your Ranger. This is especially important for model-year specifics and regional variations.

1. Provide your VIN to a Ford dealer or use Ford’s official VIN tool to retrieve rear axle details (ratio, model code, LSD option).


2. Cross-reference the axle code with an authentic axle code chart to confirm the exact specification and any optional equipment such as an LSD or locker.

Relying on VIN-based data ensures you have the correct parts compatibility, maintenance plan, and potential upgrade options for your Ranger.

Summary

To determine the rear differential on a Ford Ranger, start with the factory data plate or VIN to identify the axle size and gear ratio, then corroborate with any axle tags or differential stamps. If needed, perform careful on-vehicle checks to distinguish open versus limited-slip or locking units. For the most precise information, pull the exact spec from Ford’s sources or your dealership using the VIN. This ensures accurate maintenance, repairs, and upgrade decisions for your Ranger’s rear axle.

How do I identify my Ford rear differential?

To identify a Ford rear differential, look for a metal tag or adhesive label on the differential housing, which contains a code indicating the ring gear size and ratio. If the tag is missing, you can identify it by counting the cover bolts, measuring the ring gear diameter or housing width, or by performing a manual spin test on the wheels to check the differential type (open or limited-slip). 
This video shows how to decode a Ford axle tag: 50sBSK GarageYouTube · Oct 23, 2020
Using the identification tag or label 

• Location: Tags are typically bolted to a cover bolt, while modern labels are often found on the axle tube near the wheel. 
• Reading the code: The bottom line of the tag/label often contains the most crucial information, such as a gear ratio (e.g., "3.00" or "3L00" for a locking differential) and the ring gear size (e.g., "8.8" for an 8.8-inch axle). 
• Resources: You can use online resources like FORDification.com to decode the full axle code, which includes application and year information. 

This video shows how to identify the differential type by spinning the wheels: 55sAutorestomod Manic Mechanic Gasoline MediaYouTube · Sep 8, 2016
Identifying without a tag

• Counting cover bolts: The number of bolts holding the differential cover on can help narrow down the type (e.g., the Ford 9-inch has 10 cover bolts). 
• Measuring components:
  • Ring gear size: This is the diameter of the large gear inside the differential. A "9" indicates a Ford 9-inch, and "8.8" indicates an 8.8-inch. 
  • Housing width: Measure the distance between the axle flanges on each axle tube. Ford 9-inch differentials came in several widths, from 57-1/4" to 69-1/4". 
• Differential type (open vs. limited-slip/locking):
  • Lift the rear of the vehicle so both wheels are off the ground. 
  • Spin one rear wheel. 
  • Open differential: If the wheel spins freely in one direction, the other wheel will spin in the opposite direction. 
  • Limited-slip/locking differential: If the wheel spins freely, the other wheel will spin in the same direction. 

This video explains the visual difference between Ford 7.5 and 8.8 rear ends: 56sRegular Car ReviewsYouTube · Oct 30, 2015

How do I know if I have a 3.73 or 4.10 gear?

And since we live in the day and age of 2025. Uh if you're curious. You can easily. Google you know uh the number of teeth on a ring gear.

Where is the axle code on a Ford Ranger?

Step 1: Locate the Axle Code
View the Safety Compliance Certification Label on the driver's side, front or rear door panel. 2. Find the word AXLE under the bar code.

Does the VIN number tell you the gear ratio?

You may be able to tell the gear ratio from a vehicle's VIN by using an online VIN decoder, though not all manufacturers include this information in the VIN itself. If the gear ratio is included, it will likely be in the Vehicle Descriptor Section (VDS), which are the 4th through 8th digits of the VIN. For many vehicles, a sticker on the driver's side door jamb or on the vehicle's build sheet or owner's manual is a more reliable way to find the gear ratio. 
How to check the VIN

• Use an online VIN decoder: Enter the full VIN into a free online decoder. Some manufacturers have their own decoders, such as Mopar's decoder. 
• Look for the gear ratio code: Some VINs will have a code within the VDS that represents the gear ratio (e.g., "3731"). 
• Consult the manufacturer: If the VIN decoder doesn't provide the information, contact the vehicle manufacturer for assistance. 

Other methods to find the gear ratio

• Check the vehicle sticker: Look for a sticker on the driver's side door jamb or on the vehicle's build sheet. This sticker often contains detailed information about the vehicle's equipment, including the axle ratio. 
• Look at the differential: Some differentials have a metal tag with the gear ratio stamped on them, or there may be a sticker on the axle itself. 
• Consult your owner's manual: The owner's manual or other paperwork from the vehicle's purchase often lists the gear ratio.