I have a 06 Ram with the 5.7 Hemi. It is up to 71000. I have noticed in the last couple of months that when driving, the truck vibrates. It feels like more than a tire issue. Then today it vibrated horribly, especially around 30 up to 45 and even at 70 the motor just did not feel smooth. I don't think bad gas is it cause yesterday was the same fuel as today and it felt ok. Is there any known issues with these trucks or trans that would make it feel that way? Only thing I did today was change oil(not the brand). It is getting due for a trans filter and fluid change but will that help shuddering? Thanks

Is the shudder felt in the steering wheel or whole truck? When you're on the throttle or coasting? Low engine RPM or high engine RPM?
2wd or 4wd?

It can be felt a little in the steering wheel but mostly I can feel it with my butt. The seats and evrything inside shakes. Is worse accelerating but can still feel it when off of the gas. If I remember at 40-45 the rpm is 2500-2800 then comes down to 2000 at 65-70. In 2wd

Check your u-joints.

Check the u joints. These newer dodge trucks eat u joints weather it be a 3/4 ton or 1/2 ton.

U joints? I had 165,000 miles on a 2002, NO u joint problems. 33,000 on a 2006 NO ujoint problems. Now, 75,000 on a 2007 with no u joint problems. I have towed with each truck, and I USE all the power these motors have. My previous u joint problems in other cars were most noticeable over 55 mph.
The shudder problem....My 2007 had a shudder that felt as if I were trying to accelerate on flat tires. It turned out to be a defect in the MDS system. One intake lifter went bad and played hell with the whole motor. It took 2 dealerships to figure it out at a cost of over $4000. A code reader might be of help to you. At least it may eliminate the motor as a possible problem.

Why not start with the easiest things to check first? Hate to see someone tear down their engine or trans then find a bad u joint. JMHO.