Driveline vibration at speed

[MOPARJ]

Been noticing a driveline vibration in the Duster. Running a A-833 OD trans with a 8 ¼ rear with 3.21 Sure Grip. Tires are 255/60/15. At speeds above 73 mph, I feel a pulsating vibration in the driveline, much more present on deceleration. It isn’t severe by any means, but it is there. Upon popping the trans in neutral, the vibration is still there at speed, just easier to hear. If put back into gear and accelerating from that point, or if left in gear and accelerating, the vibration lessens or goes away entirely. I crawled under the car and checked the rear u-joint and the yoke/pinion seal. No play there. There was no play in the front u-joint itself either, but just a little play with the front of the driveshaft going into the tail of the trans. I would think that some play there would be normal.


There is no vibrations upon acceleration and the driveshaft to yoke angle should be good. Maybe the driveshaft is slightly out of balance? Last balanced it about 6 years ago when I shorted the driveshaft when I put the 8 ¼ rear in. Think this is an urgent issue?

 

[daddio4048]

I would check tires for out- of- round issue possibly. Can be done real easy on driveway.

 

[TrailBeast]

Not yet it isn't an urgent issue, but I would also put it up on stands and make sure it's not a tire.
Also know that no play in a joint doesn't mean it's not a joint.
They can be dry inside, tight and be off center.

At 70 mph it's very likely a tire, because a ujoint will usually change when you let off the throttle.