What littlered said. Also check the ubolts holding the leaf springs, double check the shocks that you put on to make sure they are the right length /part number for your truck, make sure the shock bolts are tight as well. Did this violent shaking start happening after you replaced the shocks, or was it fine for a while, and then it randomly started losing control over bumps??
In the meantime, when you go over bumps try to just coast over them, instead of accelerating or putting on the brakes. Braking over bumps will take up your suspension travel before you hit the bump, making it actually ride rougher. If you accelerate while going over bumps, the rear axle wrap will be even worse than it already is on our lightweight trucks and your back end will jerk around like nobodies business lol.
Also check your lugnuts to make sure they are properly torqued...my 4x4s should be at 100 ft lbs.
2004 4x4, ex-fleet vehicle. 4.0 v6 with 110 k, 4.10 gears.
Modifications: Whelan hidden strobes, Ion 174 alloys, yokohama geolander at 235s, billet grille, airbox mod, Dynomax exhaust. slight torsion crank. More to come!!