For a quick test, push down on a corner of the car, if it springs back to its original position without bounceing up and down, the shocks should be OK. If you see the car bounce up and down a couple of times or so before the motion stops, then the shocks are probably finished.
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record