x(whatever number we're on), get lift springs, or get an AAL. I had an AAL on my first truck and it pick the back end up to stock height and wasn't that much rougher.

 

You're not going to find a rear shackle that will fix your sag and give you 4" of lift. If your springs are worn out you'll need a 15" shackle to accomplish that. that would not only throw your entire rear suspension out of whack, it would also be tippy and unstable.

For what you want new springs are the only way to go...

 

Ok got it new springs for sure maybe shackle too. What is an AAL?

 

You definately don't want a shackle long enough to get your height back to stock or lifted. As said before, way too tippy and unstable.
Also you don't need a shackle with the brace in the center. All that does is cause your spring bushings to wear out faster, especially if you off road it much. A good quality, thick walled shackle will be your best bet.

x2 on replacing rear springs.