Description
Part number RD129, the ARB Air Locker Differential for the Toyota 8.4 in. rear axle, delivers pneumatically operated, on-demand locking traction on the 30-spline rear axle, fitting all gear ratios — covering 1996–2015 Toyota Tacoma and 2000–2006 Toyota Tundra.
IMPORTANT: The RD129 fits the Toyota 8.4 in. rear axle (30-spline) as follows: Toyota Tacoma 1996–2015 and Toyota Tundra 2000–2006 (Gen 1, through the body-on-frame generation). Buyers with a 2007 or newer Tundra should verify their axle configuration, as a different ARB Air Locker part number may be required.
The RD129 is designed for the Toyota 8.4 in. rear axle with a 30-spline, 1.31 in. shaft configuration, covering all factory gear ratios. Vehicle coverage is as follows:
- Toyota Tacoma: 1996–2015 (Base, DLX, Limited, Pre Runner, S-Runner, SR5, SR5 Prerunner, TRD Sport, TRD Sport Prerunner, X-Runner) with 2.4L, 2.7L, 3.4L, and 4.0L engines
- Toyota Tundra: 2000–2006 (Base, Limited, SR5) with 3.4L, 4.0L, and 4.7L engines
The ARB Air Locker replaces the factory open differential carrier with a locking unit that, when activated, prevents the internal differential gears from rotating relative to one another. The result is that both rear axle shafts are driven at identical speed, tied directly to the rotation of the ring gear. Maximum tractive force is delivered to both wheels simultaneously regardless of surface conditions. When deactivated, the unit reverts to normal open-differential behavior with no effect on on-road drivability or driveline wear.
Activation is pneumatic, controlled from inside the cab via the included actuator switch and solenoid valve. The switch signals the solenoid to supply air pressure to the differential’s internal locking mechanism. ARB’s patented “timed” locking mechanism provides high-engagement strength and ultra-fast unlocking response. Because actuation is air-pressure-based rather than centrifugal or clutch-based, the driver can engage and disengage the locker at any vehicle speed, allowing precise traction management on the trail without stopping. An air compressor capable of supplying adequate pressure is required for operation and is sold separately.
The RD129 features a two-piece steel carrier construction with minimal internal moving parts, designed for maximum mechanical reliability under sustained off-road use. The annular seal is steel-reinforced and elastomer-bonded, engineered to maintain integrity across extreme temperature ranges. ARB backs the RD129 with a 5-year warranty.
- Fitment: Toyota 8.4 in. rear axle, 30-spline, 1.31 in. shaft, all gear ratios
- Toyota Tacoma: 1996–2015 — Base, DLX, Limited, Pre Runner, S-Runner, SR5, SR5 Prerunner, TRD Sport, TRD Sport Prerunner, X-Runner | 2.4L, 2.7L, 3.4L, 4.0L
- Toyota Tundra: 2000–2006 — Base, Limited, SR5 | 3.4L, 4.0L, 4.7L
- Pneumatically operated locking differential — engages and disengages at any vehicle speed
- Patented “timed” locking mechanism provides high engagement strength and rapid, positive unlocking
- Two-piece steel carrier construction with minimal moving parts for maximum reliability
- Steel-reinforced, elastomer-bonded annular seal rated for extreme climatic temperature ranges
- Kit includes: Air Locker differential, actuator switch, solenoid valve, air line, and bulkhead fitting
- Air compressor required for operation — sold separately
- Color: Silver | Material: Steel
- Warranty: 5 years
- Sold individually
| Part Number | RD129 |
| Brand | ARB |
| Product | Air Locker Differential |
| Position | Rear |
| Axle | Toyota 8.4 in. |
| Spline Count | 30 |
| Shaft Diameter | 1.31 in. |
| Gear Ratio | All |
| Activation | Pneumatic (air operated) |
| Material | Steel |
| Color | Silver |
| Warranty | 5 Years |
| Prop 65 | No |