Ok I have a 2013 Dodge 3500 dually 4x4 diesel. For the past 3 months it has begun to bounce at speeds of 23 to 29mph. After that it smooths out. And becomes a - minut vibration. I have put brand new tires on and changed all shocks. I have air bags on the back since it was new. It's even worse when I'm pulling my 40ft gooseneck. Any idea's?

 

Check you u-joints in the rear drive shaft. Sounds like you may have one that is going bad.

 

If they are bad, will you change them yourself? Just did my 12 and it was a long weekend. I can tell you a couple of tips.

 

Check your center bearing too!

 

Shoot, mine has been doing that since new!!!! happens around 20 to 45 mph. Dealer has balanced the tires but still have the problem and they don't seem to inclined to correct/fix/acknowledge that there is even a problem with it it.
Thinking about moving to a different Company.

 

Rode in a Foremans 2014 Ram 2500 with a gasser and it felt like a bucking bronco on a road that I drive daily and have never felt anything with my cars or trucks.

Can't help but your not the only one, to me though it felt rear suspension related.