Welcome to JF!
It would be a big help to our online diagnostic team if you were to fill out your forums profile for your jeep. It just gives us a reference point from which to start. If you are unsure what you actually have, post up pics of the axles, engine bay, and all around the Jeep and post them in this forum: http://www.jeepforum.com/forum/f12/n...ofile-1512909/
Someone will contact you in those forums to help filling out your profile.
As for the 4 inches of lift and such, there's a sort of a lot of opinions and ways to figure out what you really need vs. what you may think you want. Try searching the YJ forums for LIFT threads and read up on them.
91 YJ "Alice" 2.5L AX5 D30/35, Rock sliders, Monsta Daughter&Dad Project
Yellow Jeep Club Club #91
05 LJ Rubi "Ghost" 4.0L Auto NV241 Rock-Trac D44/44 lockers, 4" Currie Lift, 1" BL, 33s, hardtop