Have 3" spacers on front 2014 shocks, What for Rear?

Found some newer shocks for my 06 which I been wanting to lift. 2014 Shocks with 3" Spacers and rear shocks that have 13,000 miles on them. Since I just got the Leaf recall done should I go with Blocks or get add a leaf?
Also why do some Lift kits have Spacers for dropping the belly pan and differential I think it is? Am I going to need that aswell?

 

With that upfront, you might as well just put blocks in the rear same low cost. Differential drop is unnecessary but the intent is to improve cv angle.

 

I'm thinking about just throwing in 1.5 inch block in the rear just to level my truck out with the front without adding another leaf.

 

Before and after CV angles: