I have never used them on the front of a rig. I had a set on the rear of one of my old plow trucks. I plan on installing a set I robbed from a 99 I stripped a few months back on the rear of my 86.
I have added into the front spring pack a rear positive arch spring to my plow trucks before. Have used from Chevy, and Ford. Ford rear leaves are 3" wide, they seemed to fit / look better being the same width.