I hope someone here can give me some advice as to what's going on with my Suburban... A few months ago I started experiencing some intermittent wobble in the front end when I would hit the brakes..Since then, I've replaced the worn Steering box, had the front wheels repacked and tightened, complete tire rebalance and rotate and new shocks. Over the past few days, the wobble has gotten 1000% worse, now occuring at speeds over 35 MPH when I tap the brakes. There is no apparent shake or wobble while I'm driving, I can get the truck up to 75 without any problems and the steering is straight as an arrow! However, if I even hint at tapping the brake pedal, the truck shakes wildly (It feels like the wheels are coming off!)! One part I know it needs is an upper ball joint (but it has barely a bit of play in it) and every shop I've had it to cannot figure out what's causing the problem! Can anyone shed some light on this? This things is now a dead horse in my driveway because of this! I've had the front end checked, and with exception to the ball joint, everything is tight. I was told that it's possible the king pins are shot, but I have no mechanical experience with a 4x4, so I don't even know where to look and how to check... It's an 86 GMC Suburban K2500 4x4... Thanks in advance for the help!