I did on my 136 inch 1500. It lowered the van a bit over 2 inches which I wanted so now the rear is 1 inch higher than the front, not 3+ inches higher. The ride is very nice and since my conversion is very light and I dont plan on carrying weight I am happy. KOV and I did it in about 1 1/2 hours with just a hydraulic jack and a couple of 3/8 by 1 3/4 inch bolts to use as center bolts. SOOOFT ride!
It's been discussed a lot, as well as adding air bags, re-curving the OEM leafs springs to sit lower, etc. Just enter "leaf spring" into the white search bar in the upper right of this page and quite a few hits come up.