2003 Excursion Drivetrain Problem
 

My vehicle is a 2003 6.0L Excursion (4 x 4) with 115,000 miles. Several months ago we began to notice odd sounds coming from underneath the truck. First there is a rattle (similar to tin cans banging against one another) followed by a "thud" or "clunk." The rattle is not loud and it is difficult to hear if the windows are closed. The rattle occurs at intermediate speeds 40 - 70 mph and continues until the truck slows to nearly a complete stop. This is always followed by the clunk............then the rattle is gone! The truck is shifting fine but I still took in to the Ford dealer who turned up nothing transmission related. My local mechanic replaced two worn bushing in the front end but could not identify other potential problems in the drivetrain. At first I suspected U-joints but apparently they are tight. This is an intermittent problem, i.e., I can drive the truck for several days and I don't get the rattle and clunk. I should also mention that except for tires and brakes all drivetrain components are original stock components.

Not sure what to do now. Any suggestions appreciated.

BC