Just sounds like a 20 year old suspension set up. All new bushes shocks and an lsd should wake it up. mrs ute had a fair bit of roll I did bigger shocks 600-1000lbs/inch progressive rear springs, rear s pack sway bar and a tight lsd .
I'd definitely shim the lsd they wear pretty quick 20k ago hers shuddered in car parks like a locky now in the dry you have to get off in second occasionally because you can feel it try and slip