I have a 1993 f350 4 wheel drive.  When I go over a bump like RR tracks, I get a terrific wobble that I can only stop by putting on the breaks. Any suggestions?  

Is it a TTB or solid axle (should be solid but a few were made with D50 TTB's)  

solid axel  

Is it lifted? Stock? Big Tires? High Mileage? Gas or Diesel?  (trying to get a little background on it)  

3 inch lift. gas 351. 315 75 16 pro comp tires. 112k miles  

Okay, first check all the steering linkages (rod ends, idlers, steering box and everything) Next jack up front axle and check for play in bearing and axle ball joints. If they are tight too then you may have a caster angle issue on front axle. This is not had to fix on a solid front axle with leafs as you can shim it. Are tires wearing even in front or cupping?  

This is a new thing.  I have had the truck a year with no problem and I havn't done anything to it.  The tires are wearing good.  Everything seems ok.  There is some movement in the for ends.  I havent lifted it up to check anything else yet  

The rod ends I ment to say  

Sometimes the caster and toe-in can kinda be border line is setting and make front end a little unstable but it is held stable with steering but when linkages get a bit worn and you hit a bump it can shimmy and shake