Ok, here is the deal. I recently went to a high cross-over type (drag-link above spring to a Avalanche eng. arm, tie-rod in factory location) to try to eliminate an odd problem I am having on my front SOA D44 in my YJ. The draglink/tie rod are more or less parallel now. The problem I am having is that when I am going anywhere from 20-40 MPH and I hit a mild bump my tires start oscillating violently from left to right as well as the steering wheel. It is only stopped by slowing down to a close stop. I was hoping my new setup would correct this, but it is obviously a problem somewhere else. At what angle should the tie-rod arm on the knuckle be with the ground? Parallel? It is close, but could be better with some shims. My heims and ball joints(knuckle) are all fairly new with a minimal amount of wear. My next guess would be a worn out PS box which I am going to get rebuilt along with a hydro assist upgrade. Does anyone have any other suggestions?

Sounds like a castor problem to me. I had the same shake on my Jeep. Unbalanced tires, no steering stabilizer or shocks and 5 deg on the flat knuckle were doing it.

I added a 9 deg steel shim and took it to -4º, added steering stabilizer and shocks and now drives like a champ...

Also check for alignment, wich I think is adjusted by your tierod's lenght. Place marks on the tires then turn them and measure, you should be toed in by like 1/8th of an inch...

HTH

There was a thread a while back about "death wobble" which is what you are describing. Toe, caster, and sloppy bushings and rod ends were the most common cause. Also if you have a track bar the drag link should be parallel with it to prevent bump steer. If you don't have a track bar the drag link should be as level as possible.