I've never seen a 2.5L YJ get by without either a SYE or a TC drop with a 4" lift. Check your rear slipyoke and see how far out from stock it is (the slipyoke will be shiny where it used to be inside the tailcone).
You'll also want to check the angle of both rear ujoints, making sure they're the same angle (pinion and tc output parallel) and within proper operating range.