I have a vibration when i am down shifting so i thought it might have something to do with the clutch/flywheel so i took it in and they replaced the clutch but said it already had the solid FW and now that i have it back i still have the vibration, any ideas what it could be? also just since i have it back i have a small noise at idle but as soon as i press the clutch in it goes away. any help would be GREATLY appreciated

1 ujoint was chanced 41k miles ago
the rest of the rear ujoints, center bearing and front driveline were changed 15k miles ago

 

I was going to say U joints as I had a problem at under 28,000 miles on mine. Dealer said it was drive line angle and normal. About 5,000 miles later I took it back and they changed out the drive shaft as the sealed U joints were shot. Not sure how much later but a couple of years and one of the U joints was powdered when I replaced it. A few years later I ended up replacing the U joints again as I had one that was defective from the factory in that it would not allow any grease into one side.

Do your new U joints have grease fittings? Another possibility is the carrier bearing if you have a long bed.

 

The first one I changed is greaseable but I'm with you that it's probably a ujoint. The carrier bearing was changed recently.

 

If you can feel the vibration at very low speeds and the rythum is faster than wheel rotation, I would suspect u joint.

When mine went bad you could see a bit of rusty grit around the u joint seal, but you might have to pull the shaft and flex the joints by hand to find one that is seizing up.

I also had a vibration at higher speed that turned out to be a broken belt in one of the tires. There was a defect but you really had to look/feel the tire closely to detect
It.

Good luck.