Maybe some had this with their truck. I can here a noise that is made with the revolution of the drive shaft(or at least that's what it sounds like). You can here in the truck but not outside. From 0-10 mph you can hear it turn, slow down the noise slows, speed up the noise speeds up. After 10 mph or so you lose the noise to road noise so if it's there I can't tell. Had a metal binding feel in the seat of the pants feel and that was the U-joints.
Had FORD change the U- joints and checked the carrier bearing so that's eliminated. If it's in the rear gears what might it be. Figured just to keep driving till it broke or got worse to tell where it's coming from. They couldn't figure the noise out and I didn't feel like having them do a fishing expedition on the truck.Truck in sig. Any suggestions?

 

does your driveshaft have the double cardon joints at the tranny end? if so, could be the ball and socket joint that connects the flange piece to the driveshaft. It has needle bearing and grease inside of it too. Maybe they didn't rebuild it when they did the joints.

 

It looks the same as the rear U-joints, flange and U joints. It sounds like it coming from the back of the truck, probably will have to wait till it gets louder then will be able to pin point it.
Will have to just turn the radio up louder.

 

That was my thought as well. Had that issue with my drive shaft in my 99 superduty with a 5.4 and ignored it. Ended up having to have my drive shaft rebuilt and a new rear main seal in the tranny. Just don't ignore the noise I learned the hard way!!

 

"Double carbon joints at the tranny end" is this in the transmission end?

 

a double cardon joint is the u joints at the tranny end of the rear shaft. In old days you only had one u joint on each end of the driveshaft. Now for more operating angle, the tranny end has two u joints connected by a third piece of the shaft. If the third piece were removed, the tranny flange end and the long part of the shaft would only be held by a small ball and socket assy. The ball and socket have needle bearing inside that can go bad.

 

Thanks for the explanation. Checked google for a image, no that's not on the truck.

 

Just an update. Took it to the shop the noise is the pinion bearing. Metal shavings in the oil from the bearing. Replacing pinion bearing, seals, oil. Should be good to go in a couple of days.