For a 3" XJ lift, here's some hints:
Swap the pitman arm with one from a ZJ, it is 1" lower than the XJ, and 2" lower than a TJ arm and will help prevent bump steer. 99% of the aftermarket XJ/YJ/YJ drop pitman arms are actually stock ZJ pitman arms with the Mopar part number ground off!
Remove the rear sway bar if equipt. If you don't, with certain wheel offsets, the ends of the bar will rip out the sidewalls of the tires on bumps.
Extend the front sway bar links. You can buy longer ones, or cut the stock ones and extend them with steel tubing welded in to extend them the same amount as the lift.
You may need to drop the transmission crossmember to make the rear driveline stop vibrating. About 1" will usually do it. Simple spacers and longer bolts are needed. Flat plate spacers are less prone to getting twisted off if the crossmember hits a rock.
The kit should come with directions for relocating the axle end of the front trac bar. Post here for further instructions if it doesn't.
For a real budget lift, ZJ V8 "Upcountry" package front springs with double insulators under the springs will lift the average XJ about 1-1/2" maybe up to 2" depending on accessories. If you add a winch or a heavy bumper, the ZJ V8 springs will level it out to stock height.
For rear springs on a budget, it's best to get an add-a-leaf that extends the full length of the stock spring, if they are shorter than the eyes, the stock spring will warp near the ends and look like a upside down W. For a better lift, replace the springs with a good set made with a "Military Wrap"
Spacer blocks can be used to lift the XJ rear, make sure to use only iron or steel blocks, and use a torque wrench on the u-bolts, rechecking the tightness often.
If reusing the stock lower control arms, they can be beefed up by welding a plate along the bottom to box them in.
Be sure to loosen all the control arm and spring bolts at the axle and frame ends, so that the bushings can rest in the null position, then once the lift is done, retorque the bolts to spec. If you don't, the bushings will be twisted at ride height, greatly shortening their life.
You will need new shocks. I like the Rancho 9000s for the adjustability, but other premium brands work well too.
After installation, and before the test drive, verify that the brake hoses are able to handle the added lift, and that the tires are not going to rub them at full lock to lock turns, full extension or compression of the springs.
