LMM: 3500HD dually driveline vibration

[fastline]

Didn't realize I had an issue until I put about 2500# in the bed the other day. A mild, yet obvious vibration occurs around 50-55mph. Vibration is apparent under load (throttle up), or on decel. However, if I just roll out of the throttle a bit so there is no positive or negative load on the driveline, the vibration seems to go away.

I cannot determine for certain it is not the tires but this does not feel like tires. It feels like driving over the grooved concrete we have in certain places for traction on the streets.

The noise or vibration seems to come from the front half of the truck, and possibly the Tcase or carrier bearing area. I am looking for ideas to better source the issue?

 

[catmenace]

I had the same issue with the carrier bearing. Eventually I went with a 6" single driveshaft.

 

[weazel]

Can you hear any high pitched squeaks when you take off? Sometimes when ujoints start going bad they’ll squeak.
Also check your transfer case to transmission bolts for tightness, just throwing out some ideas on things to check. I had a transfer case come loose and cause weird vibrations, but was also indicated from trans fluid leaks lol.