All XJs were built as a "Unibody" design with the body and frame rails tied together as one piece as opposed to a body on frame design. All XJs have solid axles front and rear. The suspension is coils/leaf springs. All XJs came with disc/drums brakes.
Dimensions
(small differences may occur depending on optional equipment or trim level)
The body comes in both 2-door and 4-door styles with a rear hatch (liftgate).
In 94 side-impact beams were added in the doors and roof was strengthened. The 3rd brakelight was added to the top of the liftgate.
In 96 the body structure was strengthened some although it was not noticeable in appearance.
In 97 the body (and interior) was redesigned to freshen it up a bit. Most noticeably it gave the body smoother lines by changing the bumpers, flares, and moldings. The front fender was trimmed just below the headlights and replaced with plastic bumper endcaps that wrap around to the wheel well. The liftgate was also changed from fiberglass to sheet metal in this year. The windshield washer bottle was also moved to the inside of the drivers side front fender. Engines
2.5L I4 carburated - 105 hp @ 5000 rpm, 132 ft lb torque @ 2800 rpm - used in 84-85 models 2.5L I4 TBI (fuel injected) - 117 hp @ 5000 rpm, 135 ftlb @ 3500 rpm - used in 86 and updated in 87-90 to 121hp 2.5L I4 MPI (multi-port injection) - 130 hp @ 5250 rpm, 139 ft lb @ 3250 rpm - used in 91-00
GM 2.8L V6 - 115 hp @ 4800 rpm, 145 ft lb @ 2400 rpm - used in 84-86
Renault 2.1L 4cyl. Turbo Diesel - 85 hp @ 3750 rpm, 132 ft lb @ 2750 rpm - used in 85-87
Italian VM 2.5L Turbo Diesel - 140 hp, 236 ft lb torque - used in overseas XJs
4.0L I6 EFI "Power Tech" - 177 hp @ 4750 rpm, 220 ft lb @ 4000 rpm - used 87-90 4.0L I6 MPI "Power Tech HO" (High Output) - 190 hp @ 4750 rpm, 220 ft lb @ 4,000 rpm - used in 91-95 and updated in 96-01 to 225 ft lb torque @ 3000 rpm (00-01 models use a distributorless ignition system)
Transmissions
Manual Transmissions AX4 - 4 speed manual - manufactured by Aisin - used 84-86 with 2.5L I4 and 2.8L V6 engines T4 & T5 - 4 & 5 speed manual - manufactured by Borg Warner - used 84-86 with 2.5L I4 and 2.8L V6 engines BA10/5 - 5 speed manual - manufactured by Peugot - used only up to 89 AX5 - 5 speed manual - manufactured by Aisin - used with 2.8L V6 and 87+ with 2.5L I4 AX15 - 5 speed manual - manufactured by Aisin - used with 4.0L I6 engines NV3550 - 5 speed manual - manufactured by New Venture - used in 00-01 in SE models with 4.0L I6 engines
Automatic Transmissions Torqueflight 904 - 3 speed automatic - used 84-86 with 2.8L V6 and 2.5L I4 engines 30RH - 3 speed automatic - used with 2.5L I4 engine 94?-00 AW4 - 4 speed automatic, electronically controlled - manufactured by Aisin - used from 87-01 (87-91 models include a Power/Comfort button that adjusts the shift points)
Transfer Cases
The transfer cases used are all chain driven with aluminum housings. NP stands for "New Process" which is the brand, if you will. The newer ones are NV instead which stands for "New Venture". It is the same transfer case just a different name.
NP207 - "Command-Trac" part-time only - 2.61:1 ratio low range - used 84-87 NP231 - "Command-Trac" part-time only - 2.72:1 ratio low range - shift pattern 2H - 4H - N - 4L - used 87-01
NP228/NP229 - "Selec-Trac" - 4Hi(full-time) - N - 4Lo (part-time) - used 84-87 NP242 - "Selec-Trac" part-time OR full-time - 2.72:1 ratio low range - shift pattern 2wd - 4part-time - 4full-time - N - 4LO - used 87-01
Driveshafts
Front Driveshaft - On 84-87 XJs (NP207 t-case) the front shaft is a "GKN" style shaft. On 87-01 XJs (NP231/242 t-case) the front is a "double cardan" two-piece driveshaft with a CV joint at the transfer case end.
Rear Driveshaft - The rear is a one-piece shaft with standard u-joints at both ends. The slip yoke is located on the output shaft of the transfer case. On 84-95 models, the yoke slides in and out of the transfer case and is lubricated by the ATF fluid internally. On 96-01 due to a design change, the slip yoke is external (does not slide in and out of the transfer case). This slip yoke is covered with a rubber boot.
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)
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.
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
Cooling Systems
Open style - any normal cooling system used today. Opposite of closed style described below.
Closed style - has no radiator cap and utilizes a pressure bottle. This style cooling system was used in 87-90 XJs.
Airbags
Drivers side airbag (mechanical) was added in 95. Passenger side airbag was added in 97. Airbags changed from mechanical to electronic in this year also.