Go to www.naxja.com and search around.  there is an absolute ton of info
on this there.  (btw, don't create a new post there, just use the search
function.  Someone new asks this question everyday and the answers are
pretty much the same every time.)
Also, look here:
http://www.rocklizardfabrications.com/home_brew_budget_boost.htm
This is the route I'll be going on my XJ soon (with a bunch of fender
trimming :) for extra tire clearance)

Avoid blocks like the plague, there are plenty of good ways to get lift
without ruining your springs in the process.

LOTS of back posts on the subject:

4 choices: body lift 1" is fine (purists don't like them), 2" is ok, has
some issues with radiator mounts and shift lever, 3" will cave in the
body mounts if you go off road. Shackle lifts are cheap, anything over
the minimum 1-1/4" lift will stress the mounts and screw up the caster
(won't steer right). New springs are spendy when you add the shocks,
most sets are really harsh riding. Spring over has about 6" as the
minimum lift, can be an issue if not done right.

Rubicon 2.5" spring lift is your best bet. Total replacement of all springs,
good ride, decent off road. Probably won't need a slip-yoke kit.

Carl

If you like your ride, have your springs re-arced, or add a leaf if you
want to jump off higher cliffs. Just stay away from the temporary lift, and
de arc, longer shackles, as in:  http://www.billhughes.com/93-YJ-2.jpg
       God Bless America, Bill 0|||||||0
mailto:LWHughes3rd@aol.com