On my rig, the death wobble was from the pan hard/track bar, the first set up mount on the frame would actually flex side to side and the whole truck would slam side to side about 6 inches in each direction to a point that I had to stop the truck and fast or it would keep going. This is actual death wobble, called such because if kept going the truck would literally shift side to side enough that it would either roll or break parts. This has since been fixed by beefing up the mount. If you are getting the wobble on your leaf spring set up, try what has been mentioned, especially the shackle bolts, if there is slop in there, it will cause the vehicle to move side to side a little.