Please note that the Rancho RS66000 kit comes with add-a-leafs which are intended to be installed on your factory leaf springs. I opted to get their new replacement 2.5" leaf springs and the following instructions only cover the installation of them. If you are using the add-a-leafs provided, please refer to the Rancho instructions to install them before continuing.
1. Move your wheels chocks to the front wheels. Then use a 3/4" socket or lug wrench to just loosen the lug nuts on your rear wheels.
2. Use a floor jack to raise the rear end of your Jeep from the axle and then set it back down on jack stands placed under the frame rails near the leaf spring mounts.
3. With the rear axle still supported by your floor jack, use a 3/4" socket or lug wrench to remove the lug nuts on your rear wheels. Pull the wheels off and set them aside and then lower your axle so on to 2 jack stands. If you have 2 floor jacks handy, you can just use them to support your axle on either side of the differential.
4. Using a 13mm socket and a long ratchet extension, remove the 2 bolts securing the rear shocks to the frame.
5. Using a 19mm socket, remove the nut securing the shocks to the axle stud.
6. Using a 13mm socket, remove the 2 bolts securing the bump stop to the frame.
7. Using a 19mm socket, remove the nuts securing the U-bolts to the rear axle.
8. Using a 21mm socket, remove the bolts securing the leaf springs to the frame mounts.
9. Using a 21mm socket and wrench, remove the bolt and nut securing the leaf spring to the shackle.
10. Apply a liberal amount of white lithium grease to the leaf spring bushings.
11. Install the bushings into the leaf springs as shown.
12. Apply a liberal amount of white lithium grease to the crush sleeve and install it into the leaf spring bushing.
13. Place the leaf spring on top of the axle making sure that it's situated on top of the centering pin, place the factory U-bolt plate on top of it and then place the sway bar link mount on top of the U-bolt plate as shown.
14. Install the leaf spring onto the frame mount and loosely secure it in place using the factory bolt. Use a 21mm socket to tighten the bolt to 80 ft. lbs. of torque.
15. Use the new U-bolts provided with the kit to secure your axle to the leaf spring. Use a 19mm socket to tighten the U-bolt nuts to 55 ft. lbs. of torque.
16. Slowly raise your rear axle until you can install the leaf springs into the shackles and the secure it in place using the factory bolt and nut. Use a 21mm socket and wrench to tighten them to 80 ft. lbs. of torque.
17. Use the factory bolts to secure your new extended bump stop to the frame. Use a 13mm socket to tighten these bolts to 30-40 ft. lbs. of torque.
18. Using a 13mm socket and a long ratchet extension, secure your new upper shock mount to the frame using the factory bolts. Tighten these bolts to 45 ft. lbs. of torque.
19. Install your new shocks on to the axle studs and secure them in place with the factory nut. Use a 19mm socket to tighten the nut to 75 ft. lbs. of torque.
20. Reinstall your wheels or, if you got new wheels and tires, install those at this time. Use a 3/4" socket or lug wrench to tighten the lug nuts to 95 ft. lbs. of torque. Then, use your floor jack to raise up your Jeep enough to remove the jack stands and lower your Jeep back down to the ground.