2004 Jeep Grand Cherokee steering wheel shimmies back and forth so much at 45-50 mph when you hit a bump it feels like the wheels are going to fall off. Already put new shocks, steering damper and panard bar in the front end and it didn't solve the problem

I had a similar problem and it was a combination of problems. Check the linkages and tie rods also your wheels for balancing and alignment. Hope this helps.

You have worn suspension or steering parts. Put it on a rack and inspect everything.

Upper or lower ball joints bad.

Vibration from about 40-60 mph is usually attributed to wheel balancing, but the onset when you hit a bump seems to indicate play in the steering linkages (tie rods etc) or suspension members and stabiliser bar rubbers but you had that all checked out, that brings us back to the wheel balancing.

Dodge is known for using rubber bushings in everything. They don't squeak like the poly ones do but they do rot after 10 or 15 years and cause clunking noises like you described. More than likely your clunking is coming from a tie rod which is what connects your steering wheel to your tires. Crawl under the truck near the wheel and look for the steel bar that hooks up to the back of it. Have a friend turn the wheel back and forth, or grab the bar and give it a hard shake. If there is any play, the bushing is shot. You can replace the tie rod ends yourself using the old ones to compare but it will still need an alignment, so I usually let a shop do it. New poly bushings will cost a little more but you will never have to replace them again. A good alignment shop should charge less than $200

The part you are looking at is the steering damper.It can be damaged by repeated shaking but won't cause it.
Likely the condition you have is caused by bad lower ball joints.
The lowers have no grease fittings and as such, fail earlier than the uppers. There are other causes but happen less often. Your track bar mount can wear oblong, overall cumulative wear of all front end parts can produce enough side to side play to do that or the wheels may not be torqued down exactly to specifications. In extreme cases where all is good but the shaking continues, you can have additional caster adjustment added to the alignment specs. I am assuming that your tires are properly balanced?

Need to get it checked first but reckon you may have a buckled wheel, or similar. Also check tyre doesn't have a dangerous bulge in it due to carcass failure.

may have a bad tire you can balance a bad tire but will still shake

Have your front end aligned and your tires balanced.(I would try the tire balancing first)

try gently rocking wheel back an forth while wiggling the key