Hey everybody recently put 4" rough country lift in my 98zj what size blocks should I use for tranny drop???

Its a 4.0 with 3.73 gears

no more than an inch. but that's with my xj experience.

i'd say drive it to see if you even need the drop.

Why do you need the drop? Adjust your rear arms to get the correct pinion angle and that should correct any vibes, if not install some new u joints.

The pinion angles look way off and rear vibrates how do you adjust fixed control arms? In rear?

on my ZJ, I had a 4" lift. no T-case drop was needed.

Yeah but the angle from trans to front diff is way steap

I'm at 5.5" with no drop. I've seen ZJ's at 7"+ with no drop...

Like everyone else says, drive it first.

My zj was at 7" of lift for a year without a drop kit and i had no vibes.
buy some adjustable control arms.