I've got this vibration at 47 MPH. It feels like a drive line problem. Breaking and accelerating has no affect. I can take it out of gear and the vibration does not change. Has there been any common problems with the transmission or drive shaft? It's a 3.7L 4spd auto 4X4 with about 19K miles.

 

crawl under the truck and grab a hold of the drive shaft. try and turn it both ways. if there is much play than the u joints are shot. if not the shaft might be out of balance. also check your tires. see if any weights fell off, also up your tire pressure to 40lbs see if this helps

 

Sounds like either the wheels are outa balance or the driveshaft u-joints are shot. I cant imagine the u-joints going already...but stranger things have happened. Do you off- road much?

 

My truck shudders from about 50-54, and I'm almost positive my passenger rear tire is not balanced. I think a rotate and balance would be a good start.

 

Make sure you take the damn little washers off... I left them on for the first rotation and they were fine, but the second rotation one of them must have offset the rim enough cause I had a shimmy at around that speed, so I took them off and viola, ALL BETTER!

 

With 19K, I'd almost guarantee the tires need a rotate and balance. And Bolts right about the washers that hold the drums on, they are a nuisance. Let us know if that does not do it, we'll follow up with more info.