Vibration at highway speeds and letting off gas

[Jarridt]

Hey everyone I’ve got a 2006 ranger xlt that has gotten a bad vibration when letting off the gas at anything over 40 miles an hour and at highway speeds there is a slightly less aggressive vibration. I’m thinking it’s the u joints. Could anyone help me out. It feels like I’m hitting rumble strips when I let off

 

[franklin2]

Block the front tires so it will not roll.

Then jack up the rear of the truck so the rear wheels are off the ground.

Take the truck out of gear, and take the parking brake off. This is the reason you blocked the wheels, you can't have any pressure on the driveline when checking it.

Then get under the truck and turn the driveshaft by hand, wiggling it around and pulling on it side to side while looking for play in the joints. Also look for play in the front of the differential where the shaft goes into the rearend.

 

[Uncle Gump]

Not that this is a hard and fast rule... but in my experience... vibration under load I would look at u-joints and vibrations not under load (deceleration)... rear differential.