# Lockers for the TJ — Selectable, Automatic, and Budget Drop-In Options
If you wheel a TJ on anything technical, a rear locker is the single biggest traction upgrade you can make — bigger than tires, bigger than a lift. The honest order is rear first, front second. A rear locker gets most builds through most obstacles; adding a front locker turns a capable rig into one that climbs almost anything. The catch is your rear axle: a non-Rubicon TJ has a Dana 35, and a Dana 35 with a locker and 33s is living on borrowed time.
This guide covers what fits a TJ's Dana 30 front and Dana 35 or Dana 44 rear, the three locker types and who each is for, and where the money actually goes.
A locker swap touches differential setup, so the tool list depends on the locker type. A drop-in "lunchbox" locker replaces the spider gears inside your existing open carrier and needs basic hand tools plus a dial indicator. A full-case selectable locker (ARB, Eaton) replaces the entire carrier, which means pulling the diff, pressing the ring gear over, and re-setting backlash and pinion preload — that is a shop-level job unless you have done gear setup before.
Plan on a floor jack and stands, a metric and SAE socket set, a torque wrench, a dial indicator with a magnetic base, gear oil, and RTV. Selectable air lockers also need an on-board air source — budget for an ARB twin compressor or equivalent.
Selectable lockers (ARB air, Eaton electric) stay fully open until you flip a switch, so they drive like stock on the street and lock only when you want them. They are the premium answer and the right call for a daily-driven TJ. Expect $690–$760 per axle plus the air or wiring to run them.
Automatic lockers (Detroit Locker) are always engaged and unlock through ratcheting on turns. They are bombproof and a favorite on dedicated trail rigs, but they bark and clunk on pavement and change on-road manners.
Lunchbox lockers (Powertrax Lock-Right, Aussie) drop into your existing open carrier for around $250–$400 and are the budget path to a locked axle. They behave like an automatic locker — same ratcheting on turns — but install without pressing a ring gear, so a careful DIYer can do one in an afternoon.
The Dana 35 is the weak link, and this is where TJ builds get hurt. Locking a Dana 35 and running 33-inch tires puts loads on the C-clip axle shafts and tubes the axle was never designed for — broken shafts and even bent tubes are common. If you are running 33s or bigger and want a rear locker, the durable answer is a rear axle swap to a Dana 44 or Ford 8.8 first, then locker it. On a Dana 30 front, a locker is fine for most builds; upgrade to chromoly shafts if you are on 35s and locked.
Match your locker to your gear ratio plans. If you are about to re-gear for larger tires, do the locker and the gears in the same teardown — you are already paying for the setup labor once.
Budget path: a lunchbox locker in the rear runs $250–$400 in parts and is DIY-friendly. Mid path: an Eaton ELocker or Detroit at $600–$700 per axle, professionally set up, lands around $900–$1,100 installed per axle. Premium path: ARB air lockers front and rear with a twin compressor runs $1,800–$2,400 in parts before install. The compressor is a one-time cost that also runs your tires and air tools.
Related TJ axle reading: see the Dana 35 rear axle guide for why the 35 limits your locker choices, the Dana 44 rear guide for the Rubicon and swap path, the chromoly axle shaft guide before locking a front Dana 30, and the axle swap guide if you are upgrading the rear before adding traction.
| Part | Vendor | Est. price |
|---|---|---|
| ARB Air Locker — Dana 30 front (27-spline) | ARB | ~$720 |
| ARB Air Locker — Dana 44 rear (30/35-spline) | ARB | ~$760 |
| Eaton ELocker — Dana 35 / Dana 44 | Eaton | ~$690 |
| Powertrax Lock-Right lunchbox locker — Dana 30/35 | Powertrax | ~$280 |
| ARB twin air compressor (on-board) | ARB | ~$350 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.
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