I literally JUST put JK shocks on the front of my XJ with no lift about an hour ago and thought the same thing. "Boy these should barely fit in here if they're for 2-4" of lift, wtf?!"
I'm going to go ahead and second/third the JK front shocks are same length as stock XJ/TJ front shocks.
I haven't messed with the rears yet. I'm doing rear HD leafs (allegedly 1.5" over stock) and JK rear shocks this weekend. I will report back.
Build a man a Jeep, he wheels till it breaks,
Teach a man to build a Jeep, and he wheels for life.