I have an '05 3500 4x4 dually with 109K miles. Its A/T equipped (48RE). Today I had a problem that I'm concerned might be the transmission.

Started to feel a vibration today at about 40-45mph that got progressively worse the faster I drove. At 60mph it was vibrating quite badly. Clicked it into neutral and it smooth right out immediately. Dropped it back to Drive and the vibration returned. Did this a couple of times, same result.

I clicked the "Tow" button and the trans downshifted. I did this again at around 35-40 mph and the trans seemed to hunt around trying to decide what gear it wanted to be in.

I put the truck into 4x4 mode and didn't really feel anything different at slow speeds, but it vibrated badly above 45 as before.

The transmission isn't slipping or acting weird otherwise. At slow speeds and normal take off from a stop the trans seems to shift fine and act normal.

There's no Check Engine Light displayed.

If I keep the speeds under 40 its smooth and normal.

No obvious signs of a problem (leaks, high temps, discolored fluid, etc.). Thoughts?

Could this be one of the carrier bearings on the drive shaft? I've had a howl for a little while now, but not bad enough that I've wanted to deal with changing it in 0-20 degree weather.

Comments/suggestions appreciated.

 

Sounds like a carrier or a u-joint! Gonna have to get under there and check!

 

I agree with the u-joint or carrier!

 

dangerous1965 is right, thats the same thing i'd say

 

Thanks guys. You were right, it turned out to be the u-joints. The vibration is gone completely now, but I do still have the howl or growl. We think its coming from the rear end, so we'll soon be poping the cover to check the bearings.

Also discovered that the front ball joints are bad, as are the front axle u-joints. So I'll be getting that taken care of too.

Can't complain, really. The truck is an '05 with 109K miles and the only thing I've had to do to it thus far is a set of tires. The truck has been rock-solid since new!