Run a search here on "shakers" (the common nickname all use for the Pontiac part "vibration dampener") and you will get lots of info on them. Note that their functionality is the same but mounting differences between years, Camaro vs Firebird, and front and rear.
There was a guy over on a Camaro forum who cut one open to show the weight and springs that are suspended in the oil. Maybe someone here has saved that picture?
