I swapped out the stock rear leaf springs in my van yesterday and thought I'd share my findings with you guys.
I picked up a pair springs off of 2011 2500 express van for $70. Not an option for everyone I'm sure but I work and play out of my van and just picked up a 20'x8.5' enclosed trailer so I needed the extra support in the rear for the extra tongue weight and couldn't beat the price.
There was a 1.75" difference in height with the springs side by side (as pictured) not to mention the 2500 leaf springs have a lot less give when under load. Comparing the two springs the 2500 leafs where thicker, longer, didn't taper toward the ends, and had an extra leaf.
The stock u-bolts that came on the AWD where barely long enough (end of u-bolt is flush with nut when assembled) I probably could have lived with that but for some reason my driver side u bolts have warn 1/2 way through so I'll be installing all new u bolts that are a 1/2" longer asap.
Also I have to get some new shocks ordered, stock shocks where about a half inch short when the rear suspension was all the way down and the frame of van on jack stands (had to lift the rear axle to get the bolt back through the shock when putting it back together). They will probably be fine for on road use but I do take this van off road for work and play so they've got to go.
After I got everything back together I took it for a test drive down some of the worst roads I could think of around my house and if anything I like the ride better than before. feels much better on curves / corners (less body role), and the ride isn't any rougher than before.
I didn't get measurements of the van's rear ride height before and after but I would guesstimate I got a good 3 to 4 inches of lift in the rear with the normal #1000-#1500 load of tools and supplies I keep in it