I am hoping someone has an idea on what is causing my latest annoyance. There seems to be a thump, thump, thump sound that i can also feel through the floor pan. It is intermittent and only at speeds over 40 miles an hour. Mostly starts during a decel or when I'm cruisin with no pedal in it. Sometimes stops when i accelerate, sometimes gets a little worse.

The trucks going in the shop on Thursday to get the upper and lower ball joints done on the passenger side as well as a U joint on the drivers side.
Do I have a bad drive shaft support bearing maybe? Do these even have a rear drive shaft support??

Thanx for any and all answers. I will take a good look under there when the trucks on the hoist but suggestions as to where to look would be appreciated..

 

Check universal joints for rear drive shaft.

 

I was having simular noises on my 05 excursion as well. It was hard to follow the noise because it accured so erratic, but yes the noise sounds like your truck is falling apart. Anyways I took it in to the dealership and found that the ball joints on the left side were bad. I replaced them but the noise was still there so I replaced the sway bar bushings to now have the front end silent. It was so easy to replace the bushings and it made all of the difference in the world. Dan