IMLost, you'd probably benefit from new rear springs. Yours is an early car like mine and probably has progressive (coils thinner in dia at top and bottom) springs.
I noticed a considerable ride improvement after the swap. The bone jarring was gone. I'd also change the lower upper and lower spring perch seats they are most likely disintegrating.
https://www.ecstuning.com/b-genuine-...h/33531135420/
https://www.ecstuning.com/b-genuine-...m/33531136385/
https://www.iconicparts.com/springs-rear.html