in a nutshell, aal's give ~1.5 inches added to the rear. Shackles give about the same, but also provide greater articulation, shackles don't sag the leaves. Also t-bar crank will stress the steering more, because you change stock steering geometry. But not like when you add a 3in lift. With an idler arm brace and a tbar crank your steering should be okay, but if you crank too high your centerlink will be stressed more than it should.

I suggest you use the search tool and read up more. This has been discussed here since the creation of the board.