I just went through this two days ago while installing an add a leaf kit.
1. Unbolt the lower shock bolt.
2. Remove the tires.
3. Raise the truck enough to get the suspension at full drop.
4. One side of the truck at a time unbolt the U-bolts. Impact wrench helps big time.
5. Lower that side of the axle to separate the axle from the springs.
6. Get C-Clamps around the leaf springs, probably 2-3 is good, tighten them up to hold the pressure of the springs together.
7. Remove the spring center retaining bolts, 2 of them in my case.
8. Slowly loosen and remove the C-Clamps (loosen each one a little at a time till all are loose.
9. Remove the springs, it is best to clean them and mark each one with which side is forward, usually the short side is forward.
10. For the factory clamp on the springs you can bend the lips back enough to clear the removal, then bend them back when reinstalling. Or get a cut off wheel and cut the sides of the sides, you want to keep the heat down and not to cut into the spring. A cutoff wheel worked perfect for me. You can buy replacements for cheep from www.summitracing.com
11. Replace the pads, clean up leaf springs good before reassembly.
12. Reverse order for reinstallation.
Note: If U-Bolts or Spring Center Retaining bolts are rusted or dirty use penitrainting oil. If dammaged you may need to replace them and/or cut them off when removing them.