I have a 2001 L with 2 inch drop shackles in the rear. The unfortunate part of this is when I carry my ATV in the back, the truck sits very low. Last weekend I installed "Super Springs"....they attach to the top of the rear springs with roller shackles on each end. The manufacturer claims they do not effect normal ride because they only become effective when a load is placed in the vehicle.
So far i'm very pleased with the carrying ability, however the rear end of the truck is very firm without the load. I'll take some pics if anyone is interested....