actually the axleshafts are the same length, it is the hubs that are different. the WJ Dana 30 knuckles stick out a 1/4" less then the XJ ones. the hub then makes up for it by the mounting surface being 1/4" off center to make up for the pivot point of the u-joint and keep the axle the same length. here is a picture to show you what i am referring to.
WJ Hub on the left and XJ Hub on the right
XJ hub on the left, WJ hub on the right
1994 Jeep Cherokee 4x4 5 speed - 4.0, Custom lift w/ RC long arm, 35" mudders, Bushwackers, JCR Stage 3 Sliders, ORO U-turn Steering, Dana 44, Detroit locker, Dana 30 HP Detroit Tru trac, 4.56 gears, WJ 32mm Front Sway Bar, 160amp alt.
2014 Jeep Grand Cherokee Overland V8 4x4 - 5.7 HEMI, 8 Speed, Quadra Drive II, Quadra Lift Air Suspension, Tow Rig...for now.
1995 Jeep Grand Cherokee V8 4x4 - SOLD
1988 Jeep Cherokee 4.0 4x4 - SOLD