I have a 1997 Chevy 1/2 Ton w/ 5.7L and sometimes when I hit a bump in the road my front end starts shaking... The steering wheel starts shaking, and if you don't hit the brakes quick you would probley go in the ditch...
What the heck is wrong with my truck?

Certain wheel alingment settings can cause this.
Have you got a steering damper, they can help.

I would also check your pitman arm and your idler arm.

I had a truck with swampers on it and the same thing happened to me and took it in and they balanced the tires and it went away, Check your tires and have them balanced