drives normal then when you hit 50 MPH it shakes really really bad. Like everything is gonna fall out from under the front end.i've replaced all but trailing arm bushings
problem front end shimmy on 1996 Jeep Grand Cherokee
what u describe sounds like what is commonly referred to as "death wobbles" common problem with lifted vehicles and oversized tires. have u recently changed tires? if so try rotating them and or re balencing them. other causes are- steering stabilizer worn,worn tie rods and or ball joints, bad tire, front end alighnment, trac bar bushings, control arm bushings, wheel bearings. thats some of the causes i have encountered, i build alot of 4x4's lol
Your problem is the track bar. You need to torch out the old rubber and insert a newer bushing.
I am not very familiar with your Jeep but have you tried rotating the tires front to rear. Do the tires appear to wear evenly, no "scalloping" or uneven tire wear that may be due to bad shock absorbers? Does your Jeep have a shock absorber on the steering linkage to act as a steering damper, they leak or wear out causing symptoms like what you describe.
have you had the rocker arms checked?
Steering Stabilizer shock absorber needs to be replaced