You can get the 4.5" in Long or short arm kits... If you are willing to spend the money get the long arm kit... It is better all around really. Better feeling on road and kick ass performance off-road..
What size tires are you planning on running in the next question.. Me I would start with 4.5" (which I did) and then you can upgrade..
By going with a 4.5" lift you might want to put a flat skid on which will require a Body lift off no less than an inch most likley 1.5"-2" which will allow you to run 36" tires easily...
5.5" spring and a 2" BL will allow you to almost run 39" tires which is what a buddy of mine is running.
If you want to run 35's and not do anything to the Tranny skid then go with the 5.5". If you would like to do a semi flat skid then I would suggest the 4.5" with a 1.25 JKS body lift and you can run 35's. :lol: