1997 ram, violent font end shake

Had upper and lower ball joints replaced a few hundred miles ago and the truck had run just fine. Just replaced the the front bearings, axle seals, left axle shaft (Spicer brand) and right U-joint. Now at highway speeds if I hit just the right bump the front of the truck will start to shake and within a few seconds the shaking is violent, almost have to come to a complete stop for shaking to stop.
Any ideas on what is causing this?

Your help is greatly appreciated,
Bruce

You're suffering the dreaded Death Wobble.
The steering shaft bearings and or drag link are badly worn.