I have seen some threads on this topic, but mine is slightly different. I have had this truck since new (2003 Ram 1500 4x4), it now has 130,000 trouble free miles on it. Just recently, it started "shuddering" between 50-60MPH. Any slower or any faster, and the quick slight shudder is not noticeable. This is not a wheel balance issue as it is a much finer and quicker shake than a wheel would produce. The vibration is throughout the entire truck, not in the steering wheel or from the rear. If I turn off the OverDrive, the shudder disappears. Again, this truck has never had this issue before as some have documented this type of thing from new. I have checked all the mechanical driveline components (ujoints, Half shafts etc....) and see nothing loose. Looking to see if anyone else has had this and found a fix? My guess is the torque converter or control thereof, but I have seen other threads that tried this and it did not fix anything.