Clunking sound could be a lot of things.Jack up the front axle and set it back down on jack stands with the tires off the ground.Then grab a buddy and have him or her grab your tire at the top and bottom then rock the tire while you watch the ball joints.If you see them move they need replacement.If they do not move and you still have play top to bottom its your wheel bearings.If you grab the tire side by side and rock it you can see if your tie rod ends are good as well.Clunking while turning can also be busted center pin, cracked frame at box , pitman arm ends bad etc...you need to check everything. As far as driving with bad ball joints , all my square's have 35" and larger tires which is hard on parts and I have driven lots of miles with worn out ball joints with out ever having one come apart but thats not to say it cant happen. If you do have play at the joint and its very little you should be fine to drive but if its major play I would be fixing them.
