That IS how you check ball joints. You take it up on the hoist, put a jack under the lower control arm and let it back down so that the weight of the vehicle is still on the suspension and you can put a pry bar underneath the tire to see if there is any movement in the ball joints. There is generally a zero tolerance on these parts meaning if they move whatsoever they're no good. From my experience blazers and s10's are the most prone to this but no matter the vehicle they do go bad and cause vibrations. Also get it aligned after the ball joint is replaced because the camber angles will be out of specification.
Lift it. Fat chics can't jump.
flowmaster super 40 series muffler
3" shackle extentions
torsion bar crank in the front
LT285/75R16 Durango M/T's
8" flip-down monitor
converted 60/40 seats to bucket
3" body lift