One of the things I hate about jeep's is that there are sooooo many different factory configurations. For instance my 99 TJ has a four banger with a 5 speed and dana 35 and Dana 30 axles. Most models are offered with 3 different transmissions (2 different 5 speeds, one auto and a 6 speed in 2006 and up) two engines (a 2.5 four cylinder or a straight 6) and three possible axle configurations (a Dana 35 and Dana 30, a Dana 30 and Dana 44, or all Dana 44). Of course where the weak point is depends on what set up you have.
Usually the front axle shafts are weak when lifted or locked(unless you have the Dana 44 up front) and the rear Dana 35 can become weak if you go with a locker and 33's or bigger. (but this really depends on driving style). And of course there are about a billion lift options which each have + and - and each bring up new problems. For example a 2 inch lift only requires new shocks and you can run 31's while a 4+ inch lift will let you run 33's but you will need new shocks, track bar, drop pitman arm and depending on which lift (and who you listen to) possible a transfer case drop or a slip yoke eliminator. It really depends on what you have to work with and what you plan on doing. Also re-gearing is a necessity for the 2.5 with almost any bigger tire while a 5 speed with the straight 6 and 33's will be ok without a re gear.
A few good questions to ask, which will answer your questions.
1. What year, and what factory options (axles, engine, transmission)
2. Will there be suspension mods and if so how high?
3. What size tire's will be run?
Hope that helps.
2013 Toyota SR5 4runner
2012 Suzuki drz400
1999 Jeep TJ 2" lift 31's 5speed
1989 FJ62 Toyota Landcruiser
The mountains shall bring peace to the people. -Psalms 72:3
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