Stepping up from 8.8: a Dana 44 rear (TJ Rubicon donor, ZJ V8, or aftermarket crate) for 35"+ tire builds. Heavier duty than 8.8 but more $$ and rarer donors.
Above the Ford 8.8 in capability sits the Dana 44 rear. Several donor options:
TJ Rubicon Dana 44 (2003-2006): 30-spline shafts (small for D44 — TJ Rubicon used 30, not 32), 4.11 or 4.56 stock gears, factory selectable locker (e-locker), disc brakes. ~$1200-1800 from salvage. The most popular D44 donor for XJ swaps.
WJ Dana 44a (1999-2004): aluminum housing, 30-spline shafts. Lighter but not as strong as cast iron. ~$600 from salvage. Some say not a true "D44" due to material.
ZJ Dana 44 (1993-1998 5.9 Limited or HD): 30-spline, factory LSD, disc brakes. Rarer donor. ~$1000.
Aftermarket crate D44 (Currie, Ten Factory, Dynatrac): built-to-order with your spec (35-spline shafts available, 1-ton bearings, full hydroboost-ready). $2500-5000.
Swap requirements similar to 8.8: weld on XJ-spec spring perches, address brake lines, address driveshaft, set width.
Width: TJ Rubicon D44 is ~3" wider than stock XJ — you'll need wheels with less backspace or run wider fenders. ZJ D44 is closer to XJ width.
For most XJ builders, the 8.8 is enough strength up to 35s. The D44 rear becomes the right choice if: you're running 37s, you have a high-torque engine swap (5.3 LS, 4.6/5.0/5.7 Hemi, etc.), or you're doing competitive rock crawling.
Front D44 swap is even more involved (steering, axle housings, brake hardware all change). See separate entry.
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.