Adjustable lowers will let you recenter your axle in the wheel well front to back. Probably need to push it back a little if you are that high as the axle swings down and forward in an arc. Frame side drop brackets would help mitigate this.
Adjustable uppers will let you set pinion angle. If you lengthen these a little bit more than you lengthened the lowers you will tilt your diff back (clockwise if you are looking at the rear drivers tire). Just a little ought to help line up your pinion shaft with the drive shaft. This could be where you're vibration is coming from assuming you already checked all the usual suspects. Just don't go too far our your spring pads will start to face towards the back of the truck and your coils will bow.
Adjustable panhard/trackbar will let you recenter the axle left to right. If you are going to 5" in the back you either need a longer panhard drop bracket than you had in your 3" kit or an adjustable bar. Shouldn't be too bad but it will pull the axle to the side.
You may get a little more vibration in the back as you are losing the factory rubber bushing that helps absorb NVH better than the ball joints ends on the Spohn but they should let you flex a little easier/further so thats a trade off.
