Our '99 4x4 Durango suspension is shot. We pull a heavy boat all the time. I would like to beef up the rear end; but I don't want to lift it. (Durango's look gay lifted.) The leaf springs are under the axle. Any recommendations on what to do. By the way... Not that it should matter but it has a 5.9 L.
I used the timbren load helpers. That is what the shop here in town recommends for everything all the way up to large delivery trucks. They are specific to your car. They are very inexpensive and work awesome. The very cool thing is that you have a stock ride until you put a load on it. I am able to tow our boat with our explorer.
I agree with Ty, the Timbren (http://www.timbren.com/) rubber springs work well on my 2000 Durango. They are fairly inexpensive and easy to install, the Timbren spring bolts in place of the factory bump stop. I would also recommend upgrading the shocks to a ride control shock like the Monroe or the Rancho RSX.
I just put on a set of Airlift bags, Actually Tony Neal just put on a set of Airlift bags (Thanks Tony, PROPS to you man!), on my Grand Cherokee. They are sweet and work well. Make sure if you get them that they come with a low pressure sensor.