Axles
Front Axles
Dana 30 high pinion - reverse cut - 27 spline, 1.16" diameter shafts, 7.13" ring gear - used
84-99 (some axles through
91 are vacuum disconnect,
92+ are non-disconnect,
89-95 with ABS have 5-297x u-joints, all
95+ have 5-297x u-joints, all others have 5-260x u-joints)
Addenda:
84 to '87 could also be CV joint.
Dana 30 low pinion - standard cut - 27 spline, 1.16" diameter shafts, 7.13" ring gear, 5-297x u-joints - used
00-01
Rear Axles
(Note on Dana 35 axles sometimes referred to as Dana 35C - The "C" does not stand for c-clip. It stands for "custom" meaning it came from Dana unfinished.)
(Note on 8.25 axles - none of these axles were used on XJs with ABS brakes. If you have ABS, you have the Dana 35. Without ABS you could have either
axle. 8.25 axles are c-clip)
Dana 35 non c-clip - 27 spline, 1.18" diameter shafts, 7.58" ring gear, 2.62" axle tube - used
84-89
Dana 35 c-clip - 27 spline, 1.18" diameter shafts, 7.58" ring gear, 2.62" axle tube - used
90-01
Chrysler 8.25 - 27 spline, 1.17" diameter shafts, 8.25" ring gear, 3" axle tube - used
91-96
Chrysler 8.25 - 29 spline, 1.21" diameter shafts, 8.25" ring gear, 3" axle tube - used
97-01
Dana 44 non c-clip - 30 spline, 1.31" diameter shafts, 8.5" ring gear, 2.75" axle tube - used
87-89 on some(not all) XJs equipped with towing package.
Addenda: To tell C clip from non-C clip axles, look at the axle tube behind the backing plate. C clip tubes are 1 size the whole length and non-C clip are larger at the backing plate because the bearing is bigger.
Also: Model 20 was available instead of D44 in MJs and some XJs '84 to late '86 as a tow package option.
Gearing
3.07 - used with 4.0L engine / manual transmission
3.31 - only available on older (pre87?) 2 door XJs with "Fuel Economy" package
3.55 - used with 4.0L engine / automatic transmission
3.73 - found in some XJs with the towing package
4.10 - used with 2.5L engine usually, and older XJs with the "Off-Highway Vehicle" package.
4.56 - rare but can be found on some older (~ 89 ~) models with 2.5L engine and auto transmission
Addenda: The D44 came with 3.07 (86/87 only) and 3.55 stock. A few 07/86 to 09/86 2WD 4.0L with 4 speed came with 2.72 gears. (I saw 2 so far in Canada and one in the US)