Rear Locker for the Tacoma — ARB, Auburn, and Spartan Options

The Toyota Tacoma uses an 8.4" ring gear rear differential (sometimes noted as the Toyota 8" or R180 in other Toyota documentation). The 2005–2013 2nd gen Tacoma and 2016–2023 3rd gen share the same basic rear axle housing, but the 3rd gen (specifically the 2014+ carrier — which actually carries through to the 3rd gen) uses a slightly revised carrier design. Confirm your model year and axle code (on the axle tag at the differential cover) against the locker manufacturer's fitment chart before ordering.

The ARB Air Locker is the gold standard for air-actuated lockers. When the locker is disengaged, the rear diff behaves like a standard open differential — no on-road handling compromise. When you flip the switch and air pressure engages the locker, both rear wheels are locked together regardless of traction differential. The engagement is reliable, immediate, and there's no ratcheting or clicking behavior on-road when disengaged. The tradeoff is the air system: you need a compressor, air lines routed to the diff, and a solenoid. Most ARB locker installs add a dedicated on-board air compressor (ARB twin or single compressor, $400–$700).

The Auburn ECTED and Eaton ELocker are electrically actuated — the engagement mechanism is electromagnetic rather than pneumatic, so no air system is required. The ECTED engages fully when activated and behaves identically to an open diff when off. For most trail use the behavior is indistinguishable from the ARB in practice. The Spartan Locker is a budget automatic locker (always locked) — it works but creates understeer on paved corners and clicking noise on tight turns on pavement. Reserve the Spartan for a dedicated trail rig or a vehicle rarely driven on pavement.

Steps

1. Verify rear axle ring gear size and carrier application for your specific year and 4WD/2WD configuration
2. Order locker to match — confirm 4-pinion vs 2-pinion carrier if noted in manufacturer fitment guide
3. Drain rear differential gear oil
4. Remove rear axle shafts (8 nuts each side on the backing plate flange)
5. Remove differential cover; clean gasket surfaces
6. Remove carrier bearing caps (mark left/right orientation before removal)
7. Remove carrier assembly from housing — note shim positions
8. Press out OEM side gears, spider gears, and cross-shaft; install locker internals per manufacturer instructions
9. For ARB: install air line fitting in differential cover; route air line to bulkhead through axle housing
10. Reinstall carrier into housing with original shims; set backlash per spec (0.005"–0.008" typical Toyota rear)
11. Verify bearing preload with dial indicator
12. Install new differential cover gasket or RTV; torque cover bolts in star pattern
13. Reinstall axle shafts; torque backing plate nuts to spec
14. Refill with GL-5 gear oil; add limited slip additive if manufacturer specifies
15. For ARB: route air line, connect to compressor, test engagement before trail use
16. For ECTED/ELocker: route and connect wiring harness; test engagement from cab

Why it works

• ARB Air Locker delivers full locker engagement on demand with zero on-road side effects when disengaged
• ECTED and ELocker eliminate the need for an air compressor while still providing on/off-road control
• Dramatically improves traction on loose rock, mud, and off-camber terrain
• Tacoma's 8.4" rear axle is robust and handles locker loads well
• Adds real capability that no suspension upgrade can replicate in low-traction situations

Trade-offs

• ARB Air Locker requires an air compressor, solenoid, and air line routing — adds $400–$700 to total cost
• Spartan automatic locker clicks on tight pavement turns and compromises on-road cornering — not for daily drivers
• Differential disassembly requires proper tools and bearing press — not a beginner install
• Setting backlash and bearing preload incorrectly causes premature ring-and-pinion wear
• 3rd gen carrier revision requires confirming fitment by year — don't assume 2005–2023 is one part number

Tools required

• floor jack
• jack stands
• socket set
• torque wrench
• dial indicator
• gear oil
• RTV sealant
• bearing press or access to press

Parts

Sources

• ARB Air Locker Product Page
• Auburn Gear ECTED Product Page

Related

• Mid-Tier Lift with Upper Control Arms ($600–$2,000)
• Long-Travel Suspension — Expedition and Desert Build ($2,500+)
• All Toyota Tacoma guides & tools
• Browse the full DIY database

Written and maintained by an AZ wheeler and driveway wrencher. How we source guides. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.