Description
The ARB Air Locker Differential (RD119) for Ford 9-inch rear axle with 31-spline shafts, delivers on-demand locking traction across all gear ratios for Ford Bronco (1966–1986), Bronco II (1984–1986), F-100 (1975–1983), E-100 Econoline (1969–1983), E-150 Econoline (1975–1988), E-200 Econoline (1969–1974), and E-250 Econoline (1975–1980).
The ARB Air Locker is a pneumatically operated locking differential that replaces the factory open differential carrier in the Ford 9-inch rear axle. When engaged, it locks both axle shafts to rotate at the same speed as the ring gear, delivering maximum traction to both rear wheels simultaneously. When deactivated, it returns to open-differential behavior with no effect on normal street driving, fuel economy, or driveline wear.
Engagement is controlled by a dash-mounted switch that routes compressed air through a solenoid valve to the differential. The Air Locker’s pneumatic actuation allows the driver to lock and unlock the differential at any vehicle speed without leaving the cab. ARB’s patented “timed” locking mechanism is engineered for both high-strength engagement and rapid, positive unlocking under all conditions.
The Air Locker is a two-piece steel assembly with a minimal number of internal moving parts, a design philosophy that ARB states maximizes long-term reliability. The annular seal is steel-reinforced with an elastomer bonding rated for extreme climatic temperature ranges. ARB backs the Air Locker with a 5-year warranty.
- Fitment: Ford 9-inch rear axle, 31-spline shafts, all gear ratios — Ford Bronco (1966–1986), Ford Bronco II (1984–1986), Ford F-100 (1975–1983), Ford E-100 Econoline / Club Wagon (1969–1983), Ford E-150 Econoline / Club Wagon (1975–1988), Ford E-200 Econoline (1969–1974), Ford E-250 Econoline / Club Wagon (1975–1980); see eBay compatibility table for full Year/Make/Model/Trim coverage
- Provides 100% locking traction on demand without affecting open-differential behavior when deactivated
- Pneumatic activation via dash-mounted switch — operable at any speed from inside the cab
- Patented timed locking mechanism engineered for high-strength engagement and ultra-fast unlocking
- Two-piece steel construction with minimal moving parts for maximum durability and reliability
- Steel-reinforced, elastomer-bonded annular seal rated for extreme temperature ranges
- Kit includes: Air Locker differential, activation switch, solenoid valve, air line, and bulkhead fitting
- Air compressor required for operation — sold separately
- Warranty: 5 years (ARB USA)
- Sold individually
| Part Number | RD119 |
| Brand | ARB |
| Product Line | Air Locker |
| Axle | Ford 9 in. |
| Position | Rear |
| Spline Count | 31 |
| Shaft Diameter | 1.32 in. |
| Gear Ratio | All |
| Material | Steel |
| Color | Silver |
| Activation | Pneumatic (air compressor required, sold separately) |
| Kit Contents | Air Locker differential, activation switch, solenoid valve, air line, bulkhead fitting |
| Warranty | 5 Years (ARB USA) |
| Prop 65 | No |
Fitment Notes
The RD119 fits the Ford 9-inch rear axle with 31-spline shafts across all gear ratios. Manufacturer-listed applications are: Ford Bronco (1966–1986), Ford Bronco II (1984–1986), Ford F-100 (1975–1983), Ford E-100 Econoline and Club Wagon (1969–1983), Ford E-150 Econoline and Club Wagon (1975–1988), Ford E-200 Econoline (1969–1974), and Ford E-250 Econoline and Club Wagon (1975–1980).
Important: The Ford 9-inch axle platform is also used with 28-spline and 35-spline shaft configurations. Confirm your axle’s exact spline count before ordering — the RD119 is specific to 31-spline applications. ARB also offers Air Lockers for the Ford 8.8-inch rear axle (RD81) and the Ford 9.75-inch rear axle (RD150); verify your axle size and spline count to ensure the correct unit is selected.