CJ, YJ, TJ, LJ or JK?  
  This will help you identify different models. Sometimes I'm surprised to find out owners of Jeeps don't even know the difference between various models. 

CJ3B's also know as "Flat Fenders" or "Flatties", they are rare and were produced from 1953 to 1968. You may wonder what happen to the CJ-4, well there were proto types built but the model never went in to production. At least one proto type still exists waiting restoration by it's owner. The CJ5 basically stayed the same from 1954 to 1983 although they had some changes. The CJ-5 was the longest produced model. The CJ-6 was made from 1955 to 1975. The CJ-6 was essentially a CJ-5 with 20 extra inches of wheelbase (101 inches total), the CJ-6 offered the storage space of a small pickup and the mobility of a Jeep. The CJ-7 offered a compromise between the CJ-5 short wheelbase and the long wheelbase of the CJ-6. The CJ-7 was made 1976 to 1986 and are one of the most common Jeeps seen on the road today. The CJ-8 had the longer cargo area. The YJ was made from 1987 to 1995 and can easily be recognized by the square headlamps. The TJ was redesigned to include coil spring suspension and have been produced from 1997 to the present. The TJ model also went back to the traditional round headlamps. In 2004 the LJ was introduced, a stretched version of the TJ. The 2007 model year brought the complete redesign of the Jeep Wrangler, in both two and four-door models. The TJ platform was replaced by a new JK platform.

 

 

CJ

If you own a CJ-5, 7,or 8, and your not a regular down at the local off-road toy store, your vehicle has a 3 or 4 speed manual transmission, front & rear leaf springs, most likely a Dana 30 front axle, & an AMC model 20 rear axle. Most transfer cases in the later models were Dana 300's. Earlier vehicles had T-18's or T'20's.
For stock vehicles it's a good idea to upgrade the shackles and hangers for strength and safety. Steering can be improved with a shackle reversal kit, and steering box support. Also the factory U-bolt plates are a common weak point, and should be replaced with a heavy-duty U-bolt skid plate which also provides U-bolt & shock protection.
Recognizable features: Round headlights, leaf springs, & rust (just kidding!). Lug nut pattern is 5 on 5.5".


YJ

If your pink slip says Wrangler you have a YJ ('87-'95). It came stock with. either a 5-speed standard or a 3-speed automatic. Like the CJ it has leaf springs front and rear. The front axles were Model 30's (with vacuum operated disconnect), and the rears were Model 35's, with a 44 upgrade available. The transfer cases were called Command Trac (N.P. 231). Command Trac means you have a choice between 2 wheel drive & 4 high or low.
For stock vehicles it's a good idea to upgrade the shackles and hangers for strength and safety. Steering can be improved with a shackle reversal kit, and steering box support. Also the factory U-bolt plates are a common weak point, and should be replaced with a heavy-duty U-bolt skid plate which also provides U-bolt & shock protection.
Recognizable features: Square headlights, leaf springs, & swing-out tail gate. The Wranglers were lower than the CJ. Lug nut pattern is 5 on 4.5".


TJ

If you purchased your Wrangler in 97 or later it's a TJ. The TJ has a four link coil suspension front and rear. Four link means there are 2 upper and 2 lower control arms front and rear. All come stock with Model 30 front axle, and Model 35 rear axle with an optional 44. Like the YJ, all models come stock with Command Trac (N.P. 231)
The TJ comes from the factory a very capable off-road vehicle. Sway bar disconnect will significantly increase articulation (keeping all tires on the ground).
Recognizable features: Round headlights & coil springs. Lug nut pattern is 5 on 4.5".


LJ

In 2004, Jeep introduced the Wrangler Unlimited with a 10 in (~25.4 cm) longer wheelbase (LWB), a Dana 44 rear axle with a 3:73 gear ratio and the Command-Trac 231 transfer case; this model is also known by its unofficial designation of LJ. In 2005, Jeep released the Rubicon Unlimited, which has the wheelbase of the Unlimited and the off-road features of the Rubicon such as front and rear Dana 44 axles with locking differentials, diamond plate rocker guards, a NVG241OR transfer case with a 4.0:1 low range, 245/75R16 Goodyear MT/R tires, a six-speed manual transmission and other comfort and convenience options not offered on other Wranglers.


JK

The 2007 model year brought the complete redesign of the Jeep Wrangler, in both two and four-door models. The TJ platform was replaced by a new JK platform. This next-generation Wrangler was significantly larger than the existing model, with a 2 in (50.8 mm) longer wheelbase and 3.4 in (86.4 mm) wider track, though the two door model is actually 2.5 in shorter in the overall length than the TJ, allowing for better approach and departure angles. With a larger available standard tire size of 32 in, break over angle is unchanged