I just got my 96 xj about a month ago so I'm new to these. My problem is that it rattles and knocks in the front end. And at around 50 it's starts shaking until about 55. It starts again a little over 60. I don't know if it quits after that because I've only had it to 65. Where should I start in trying to find the problems?

Check your ujoints, hub bearings, ball joints. If those are all fine. Get the torque wrench out and go over the whole front end.

Could it be control arms or track bar?

If your axle is bent it could but it's more likely your ujoints or ball joints.

i have the exact same problem and i have tried all of this and nothing worked

Well I looked at it all today. Looks like all the bushing in pretty much everything are bad. Ball joints seem fine. Could it be the bushings causing it?

Have you jacked up one side of your axle and shook the tire up and down left and right to make sure their is no movement?

I sure did. No play to speak of.