Does it drive OK until 35-40 and then feel like the van is about to shake apart? If so then it is a 99% chance it is a INNER CV JOINT. Try lifting the front , letting the wheels hang and shake the inner joint. You will probably get a loose or grinding feeling as the wheel is turned BY HAND. If so replace the whole axle they are cheaper than just a joint and usually carry a lifetime warrenty at most chain auto stores.
When you replace it undo the sway bar on both sides, remove the 15mm pinch bolt from the balljoint, and PRY DOWN HARD. Be careful you dont mess up the new joint the inner joints are spring loaded internally. also there are no keeper clips on the trans side it will just slide out. You will loose some trans fluid so be sure to have the right type on hand.
Good Luck
Brad
