If it says 2" lift shackle, then it will lift you 2". A 2" lift shackle is 4" longer than stock. If one side moves up 4" and one side stays fixed, the midpoint (where the axle is mounted) will move up 2"

The lift is half of the difference in length between stock and aftermarket.
3" difference results in 1.5" lift
4" difference results in 2" lift
5" difference results in 2.5"
37" difference results in 17.5" lift

 

i used the autozone shackle set (cheap bastard) doubled them up though and bought new hardware, doubling them made included hardware useless.
i am happy with them, about a month now (daily driver no serious off-road) adds up to about 1/2" steel on each side of mount. i fig. should be fine for what i am doing.
i was also happy with the lift they provided.

 

i wouldnt even think about buying those cheap pos' from autozone. get either daystar shackles, fabtech shackles, somthing alot stronger than the ones you posted.

here are 3 diff shackles lifts that woub be good.

http://www.shop.synergyoffroad.com/p...&categoryId=10

http://www.shop.synergyoffroad.com/p...&categoryId=10

http://www.shop.synergyoffroad.com/p...&categoryId=10
(^ these are made by a guy from zr2usa.com) also the ones i have on my BlaZeR 2.

 

Well, you could always buy the cheap ones, and mod them to be stronger.

 

I just made my own out of 1/2 thick steel. Drilled enough holes to have anything from 1 inch of lift to 4. Pic is of the rear end maxed out just to see what it would look like, I ride around with it on 2 inches.