The ARB RD121 is an air-actuated, driver-selectable locking differential for the Toyota 8" IFS axle — 100% mechanical lock on demand, fully open when disengaged.
Technical specifications
Ring gear: Toyota 8" IFS / clamshell
Spline: 30
Carrier bearing: 53 mm
Shaft diameter: 1.31"
Ratio range: 3.73 & down
Material: Forged steel
Actuation: Pneumatic (air)
Engineering
Two-piece, ultra-durable design with minimal moving parts for maximum reliability
Patented, timed pneumatic locking mechanism — high strength with ultra-fast unlocking
Steel-reinforced, elastomer-bonded annular seal rated for extreme temperatures
Fully open when disengaged — no effect on on-road drivability or driveline wear
5-year warranty
Fitment: Toyota Prado 120/150 & Hilux IFS Front (Low Ratio). Toyota 8" IFS (53mm brg), 30-spline, 3.73 & down ratios. 8" IFS front (Prado 120/150 = 8"; NOT the 7.5" Prado 90 — see RD90). For 3.73 & numerically lower ratios.
Spline note: Toyota 8" IFS front differentials are typically 30 spline — confirm your spline count before ordering.
In the box: Air Locker differential, dash activation switch, solenoid valve, air line and bulkhead fitting. An ARB air compressor is required to operate (sold separately) — pair with an ARB CKMA12 (single) or CKMTA12 (twin).
