You will get at least 1.5"'s with the Eibach springs. You will need an alignment done, but there is no need for a dif drop.
I had a 2" lift and felt some vibrations and when I wnet to the eibach's, the truck drove smooth again. Plus with the 2" lift the alignment shop was just able to get my front in spec with the settings max'd out. With the 1.5" lift they had no problem aligning the truck to factory spec.
I would highly recommend these coils if you're only looking for a mild lift.
My truck with Eibach's and stock TRD shocks.