Stock Dana 30 inner u-joints are 297X (small). Upgrade to 760X (larger) requires axleshaft replacement. Spicer is the only brand worth running.
The Dana 30 inner axle u-joints connect the inner and outer axle shafts at the steering knuckle. Stock joint is the Spicer 297X (small chrome moly cap, 1.062" cap diameter). It's adequate for stock 30" tires and gentle use but breaks under heavy steering plus throttle load with 33-35" tires.
Upgrade paths:
1. Spicer 297X replacement (same size, same weak spot): use when refreshing tired joints on a low-mod truck. Cheap ($30-50 per joint). Spicer brand only — cheap parts-store joints fail in months.
2. Spicer 760X chromoly axle upgrade (PN with larger u-joint): requires replacement of both the inner and outer axle shafts with Yukon, RCV, or Alloy USA chromoly shafts that accept the 760X joint. The joint itself is 1.125" cap, ~30% stronger.
3. RCV constant-velocity (CV) joint axles: replaces the u-joint with a true CV (Birfield-style) for full-lock steering without binding. Used by competition rock crawlers. $1500-2200 per axle. Overkill for most builds.
When to upgrade: 33" tires plus regular wheeling, or any time you've broken a stock 297X joint (you'll know — the truck makes a clack-clack when steered hard).
Install: u-joint replacement on a Dana 30 requires removing the axle shaft from the housing (unbolt the spindle/hub, slide shaft out). A press helps but a vise and brass drift can work. Don't pound the caps with a hammer — you'll shock the needle bearings into failure.
Spicer brand only. Generic u-joints from FLAPS will fail within months under XJ trail use.
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| Part | Vendor | Est. price |
|---|---|---|
| Spicer 297X u-joint (each) | Spicer/Dana | ~$40 |
| Yukon Chromoly 760X axles (pair) | Yukon | ~$380 |
| Spicer 760X u-joint (each) | Spicer/Dana | ~$60 |
| RCV CV axles (pair) | RCV | ~$1800 |
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.