To get a Posi-Lok style functionality, you'll need to replace the entire front differential assembly. You can't just "build" a Posi-Lok onto your existing differential.
Here's what that entails:
1. Find a suitable replacement differential: You need to find a Dana 30 front axle assembly that already incorporates a Posi-Lok system. This is the most challenging part, as finding a used Dana 30 with Posi-Lok in good condition can be difficult. Junkyards and online parts marketplaces are your best bets. Be aware of the potential for wear and tear on a used differential.
2. Ensure compatibility: Make absolutely sure the replacement Dana 30 is compatible with your 1989 Jeep Wrangler. This includes checking the axle shaft length, bolt patterns, and overall housing dimensions. Even within the same model year, there can be variations.
3. Installation: This is a major job, not a simple bolt-on. It requires significant mechanical skill and the right tools. You'll need to:
* Disconnect the driveshaft: Disconnect the front driveshaft to prevent damage.
* Remove the old differential: This involves removing the axle shafts, brake calipers, and various other components. You'll need to drain the differential fluid first.
* Install the new differential: Install the new Posi-Lok equipped differential, ensuring proper alignment and torque specifications.
* Reconnect everything: Reinstall all the components you removed, including the axle shafts, brake calipers, and driveshaft.
* Bleed the brakes: After reassembling everything, you'll likely need to bleed the brakes.
* Fill the differential: Fill the new differential with the correct type and amount of gear oil.
4. Engage/Disengage the Posi-Lok: Once installed, the Posi-Lok system will typically have a cable-operated lever (often in the cab) to manually engage and disengage the locking mechanism. Familiarize yourself with its operation *before* hitting the trails.
Important Considerations:
* Professional Installation: Unless you have extensive experience working on differentials and Jeep axles, it's strongly recommended you take your Jeep to a qualified mechanic specializing in Jeep repairs. Incorrect installation can lead to serious damage to your vehicle.
* Cost: The cost of a used Dana 30 with Posi-Lok, plus the labor cost for professional installation, will be substantial.
* Alternatives: There are other locking differential options available for the Dana 30, such as selectable lockers (ARB, Eaton) or automatic lockers (Detroit Truetrac). These may be more readily available or better suited to your needs and budget, although they are typically more expensive.
In short, building a Posi-Lok system for your Jeep Wrangler's front differential isn't about "building" it; it's about finding and installing a pre-built differential that already has the Posi-Lok system integrated. It requires a significant mechanical undertaking. Do your research and weigh your options carefully before proceeding.
