ARB Air Locker RD121 Locking Differential - Toyota 8" IFS (30 Spline, 3.73 & Down, 53mm Bearing) Select 2003-2023

Fits select 2003-2023 Toyota 4Runner, Tacoma, FJ Cruiser, Land Cruiser, and Tundra.

The ARB Air Locker RD121 is the industry standard for on-demand traction, providing a 100% locked differential with the flick of a switch. Designed for the Toyota 8-inch independent front suspension (IFS), this pneumatically operated locker replaces your factory open differential to eliminate wheel spin by tying both wheels directly to the rotation of the ring gear. This allows for controlled, low-speed technical crawling while maintaining the smooth on-road drivability of a conventional open carrier when disengaged.

Built for the most demanding off-road environments, the RD121 features a robust two-piece design with a patented timed locking mechanism for high strength and ultra-fast disengagement. The internal steel-reinforced, elastomer-bonded annular seal is engineered to withstand extreme temperatures and repeated cycles without failure. This model is designed for 30-spline axle shafts and gear ratios of 3.73 and down (numerically lower), utilizing 53mm ID carrier bearings.

• Provides 100% traction on demand without affecting highway handling or driveline wear
• Two-piece ultra-durable design for maximum structural integrity
• Patented timed locking mechanism offers superior strength and fast unlocking
• Steel-reinforced elastomer bonded annular seal for reliable pneumatic performance
• Requires an ARB Air Compressor for operation (sold separately)

• Manufacturer Part Number: RD121
• Spline Count: 30
• Gear Ratio: 3.73 & Down
• Carrier Bearing ID: 53mm
• Differential Type: Toyota 8" IFS
• Kit Includes: Air Locker differential, activation switch, solenoid valve, air line, and bulkhead fitting