I have a 2001 Chevy HD 2500 4 x 4 crew cab with 2800 miles. At 1600 to 2000 RPM the vehicle vibrates, kind of fills like your driving down a bumpy dirt road. The vibration goes away and then comes back at 2600 RPM. The dealer replaced the drive shaft saying there was a silent recall on this item. The new drive shaft did not correct the problem. The dealer and GM customer assistance have said the vehicle is working as designed. My feelings are if the vehicle is working as designed then why did they replace the drive shaft. Has anyone else experienced a problem like this with the New Like A Rock HD 2500 4 x 4 crew cabs? If so how was it corrected.I have the 6.0 eng. with auto trans.