HUM do you have a Broken leaf spring take a look at you leaf spring stack.

Or like Dewalt378G said you'r Clocking on you'r Torsion bars mite be off.

How much lift do you have is it just a leveling kit or full blow Lift kit.

I was thinking if it is just a front end type lift all they did in the rear is install shocks and most Full lift kit that Fabteck lift use blocks in the rear I woundering did they install the same size block on both sides, or is one of the block sitting on top of the centering pin on the Leaf spring.

 

yea i would say that this kit was not installed properly in order for a truck to lean like that the suspension probaly is aligned correctly.... its really obvious in the pic but i can only see the rear...

 

Bad install! Take it back and make them fix it! You paid good money for a good job.
ALL name brand, suspension lifts are designed to have a level stance, both front to back AND side to side. Ask some folks on here to post pics of their trucks with Fabtech lifts and print a few. Take them to your installer as evidence that yours is NOT normal.
I have a Rancho 4" Suspension Lift, and on level ground, the measurement from the highest point of the wheelwell to the ground is within 1/8" all the way around.