I would appreciate any suggestions pertaining to a vibration in my mint 2004 Dodge Cummins duallie with four wheel drive. The vibration starts at 55 mph and goes away at 65 mph. However, that is the speed which I preferr to drive. I don't believe it is the tires because they have been balanced numerous times. Thanks - Hemi Joe

Do you feel it in the steering wheel or the seat of your pants? Does it go away if you shift into neutral while it's vibrating?

Thanks for the reply! No I do not feel it in either the seat or the steering wheel. It is stronger under load and maybe a little less when I take it out of gear! Thanks -- HEMI JOE

Sounds like its time to check your u-joints real close. Id unbolt the rear driveshaft and check especially the rear u-joint and center u-joint if equipped for binding or stiffness. They are very common to go bad. They may not show any signs of being bad while being bolted up so thats why you must unbolt it and move it in all directions to check it properly.

I would take a good look at the slip yoke and/spline if a 2 peice driveshaft. make sure the u-joint yokes are in phase front and back 1/2 of shaft.

the splines wear and will get sloppy on the splines(up and down), also a cause of a clunking when stoping/take offs as they clunk back and forth.

like said,R&R the shaft checking carrier bearing,slip yoke,u-joints.( if stock non-greesable..how many miles?) look for any weights welded on shaft that may have come off/look for dings dents in the tubes that can throw off balance.

also grab the yoke on the rear axle to check slop in pinion bearing, 9 1/4 axles are known to come loose.

Balanced tires does not mean they are round. Check tread for runout.