I have installed Eibach kits on 02 - 06 and they had rear height links. You won't have to replace rear shocks no matter what. I wouldn't change the torsion bar keys as this will drop the front too much. If you want the truck near level as opposed to the rake of the stock setup, leave the front alone. You can just replace the rear springs and adjust the torsion bars. Make sure you align the front-end after the height is set.