Before ordering ring-and-pinion gears, lockers or a complete third member, identify both the differential family and the actual gear ratio. Toyota used multiple ratios and multiple differential types across classic Pickup and 4Runner applications.
Do Not Assume Ratio From Model Year Alone
Factory ratio can vary with engine, transmission, drivetrain, tire package and work-truck configuration. A 1989 4WD truck, for example, was not limited to one universal axle ratio.
Check the Toyota Axle/Transmission Code
Many Toyota certification/identification labels include an A/TM or axle/transmission code. On applicable trucks, the axle code can identify the ring-gear family, factory ratio and differential configuration.
Use the code as a factory starting point, not absolute proof on a modified vehicle. Axles and third members are commonly swapped.
The Definitive Mechanical Method: Count the Teeth
If the differential is open for service, divide the number of ring-gear teeth by pinion-gear teeth. For example, 41 ring teeth divided by 10 pinion teeth equals a 4.10:1 ratio.
This is the most reliable method when the axle code is missing, the truck has been modified, or the current third member came from another vehicle.
Front and Rear Ratios Must Match on 4WD Trucks
A 4WD Toyota must use matching front and rear final-drive ratios when four-wheel drive is engaged. Do not install a 4.88 rear third member with a 4.10 front differential, or any other mismatched pair.
8-Inch vs. 7.5-Inch Matters Too
Classic Toyota 4WD trucks commonly use an 8-inch solid-axle rear differential, while IFS front applications can use a different differential family. A gear set listed for a Toyota 8-inch solid axle is not automatically correct for a 7.5-inch IFS front differential.
Special Case: Factory G144 4.88 V6 Differential
The factory G144 4.88 V6 third member is a special configuration with a unique housing/ring-gear arrangement. Standard aftermarket V6 4.88 ring-and-pinion sets are not a direct replacement for the original G144 gear set inside that housing. If you have a factory G144 unit, identify it before ordering regear parts.
Before Ordering Differential Parts
- Confirm front vs. rear.
- Confirm 2WD vs. 4WD.
- Identify 8-inch 4-cylinder, 8-inch V6/Turbo, high-pinion or IFS differential family as applicable.
- Verify current ratio from the code, rotation test or tooth count.
- On 4WD trucks, verify both axles use the same ratio.
- Check for factory locker or other non-standard housing features.
For a modified truck or unknown third member, use Fitment Help before ordering.