1995 STS Death Wobble
 

I am trying to source the potential problem(s) associated with my dreaded 'death wobble' that occurs around 50 mph. You can sometimes drive through the wobble by increasing speed but it does not always work. I have new tries installed & balanced, rims run true, front end was gone through recently with new ball joints & bushing throughout. Can a rear wheel brake drag cause this type of sensation? I have the right rear wheel heating up slightly. Wheel bearing have no play (3 & 9 o'clock).
I have been told that this year Caddy does not have a "steering Damper" since it has rack & pinion steering......is this correct?

Any help would be greatly appreciated!
Ron