Hello, I have a 2003 Dodge 2500 - 5.7L SWB quad cab 4x4.
when I am driving 60 Mph or more and I hit a bump in the road the rear of the truck shakes violently. The only way to stop it from shaking is to slow down significantly. Now I have had people says it the tires, even after getting new tires it is doing the same thing. Also I have my tires rotated every oil change of 5k miles. So I Don't think it is the tires or wheels.

Any ideas on what it could be????

 

shocks, front and rear.
broken leaf spring, booster spring
damaged bushings for rear springs.
damaged/rusted rear frame section.

old tires have an ODD wear pattern.. how are the new ones doing?

 

This^^ Need to perform a thorough inspection of the rear suspension.

 

the new tires have been on for 6 months and they are great. But still having the same issue. Shocks were my first thought, any way to tell if they are bead. I know if I push down on the bed of the truck the shocks move an inch or so, never noticed this before.

no rusted rear or damaged leaf springs that I can see, all still intact.

 

Shocks are usually good until 50k.

 

as your inspection did not turn up anything..

take it to a shop.. as this can be serious... and may cause a major failure... and maybe an accident