Eh, I strongly advise a leaf pack.
1. Your springs are already worn and sagged.
2. AAL's, Shackles, Blocks will all expedite the complete sagging out of your leafs
3. A lift shackle will kill your shackle angle and ruin your ride quality
4. Blocks will increase the occurence of spring wrap and could cause yoke/driveline damage, as well as sag out the leafs
5. AAL's can put stress near the eye of the spring and cause negative arch in the main leaf and potentially break the main leaf.
Here is a wise suggestion.
Get a 3"-3.5" leaf pack. RE's are like $175 each + $70 or more shipping. I do Tuff Country's 3" pack for $159.99 and if you're interested in them I will ship them for free ($319.98 total)
1. PM me and I'll give you a checkout coupon code for the free shipping.
2. Tuff Country's are a decent spring, fairly soft riding, and have a lifetime warranty. I installed a set yesterday actually.
3. UPGRADEABILITY! When you're ready for 4" of lift, you can add a shackle relocation kit. Brianho13 on NAXJA makes a kit for this. http://www.naxja.org/forum/showthread.php?t=956630
4. UPGRADEABILITY! When you're ready to go any higher, a 1-1.5" lift shackle will get you to 5.5-6" and you'll have adjustability in your relocation kit to keep your shackle angle.
This would be a really good way to go about it. Obviously an extra $320 for leafpacks isn't in everyones budget, but in 6 months - 1 year when your add-a-leaf or block has mutilated your factory leaf packs, you'll be wishing you bit the bullet. I know I did.