Another thing to look for is where your slip yoke on the rear driveshaft is. It pulls apart further the higher the lift and if you keep the downtravel with longer shocks/springs it can get far enough down the splines to lose strength or even come apart. I don't think you're going high enough to worry, but it is something to check. The front driveshaft CV's really don't like high pinion angles so a diff drop via bracket modification as seen on several threads is highly advisable, this helps with the angles on the axle CV's too. The pinion angle can also be adjusted with the diff drop by realigning the diff mounting holes a bit to tilt the pumpkin up a few degrees. Any good fab shop should be able to handle this.