Hi,
I made my first "How To" video, as I figured it might help some of you Deville owners. All 4 rear upper and lower Ball joint/Bushings on my 99 Deville were completely shot.
This is a pretty simple repair and restored the ride of my car to almost new :worship:
You can easily diagnose the knuckle bushings by grabbing a hold of your rear wheels, while the car is on the ground, and pull/push on the top of the tire. Mine where literally moving back and forth about 2 cm. While driving, the back end of the car seemed to be floating left and right (more than normal

)
You can buy the parts on e-bay for around $100. (Dorman P/N: 905-504)
Hope this video helps someone get his deville back on the road. Enjoy