Something is seriously worn out. There has to be some worn out bushings somewhere. I suspect upper and lower control arm bushings. Maybe a set of tubular uppers with heim joints are in order to start.
It's all energy suspension stuff. I'm probably gonna go that route just to give more adjustment. My Dad has always tossed wrecking yard parts at this car when he raced it....so knowing him when he did the disc brake swap no telling what he used...it has 68 Dart springs under the back....SMH.
