I've searched for this specific issue. I am feeling a vibration whe I get off the gas at above 40 mph. Once back on the gas it seems to go away? I can also make it go away if I load up the left side by seering hard right. once the trucks load is even or on itsl right side (again off the gas) I feel the vibration again? I was thinking driveshaft/u-joints???

Any suggestions?

 

Universal joints or possibly a hub/bearing assembly. U joint vibration is most noticeable at 35mph and 70mph. Above or below those speeds it's still there but not as bad. Loading one direction or the other doesn't usually make a difference with U joints, (on and off the gas does) that's why I mentioned the hub.

 

Possible rear end bearing.

 

Thanks for the quick response, I will check it out...

 

Absolutely, good call! A bad pinion bearing would show up when checking the rear universal joint.

 

+1 to captain hook and blazerguy. I had a simialr situation, all though the bearing was making more of a humm. And I totally overlooked when I replaced the u joints lol.

 

As these rears are usually solid-it is all dependant upon the mileage and use of the unit!
maintenance plays a factor as well.The diff cover rusts on these axles promoting fluid loss also-which leads to bearing loss! Just check the whole drive line to be sure,but seems like u-joints to me...

 

Awsome feedback guys! The vibration has also a humm to it as well. The truck has 107K on it and is in pretty nice shape, however I do know for a fact that it was not moved for over a year until I bought it...

 

When they sit like that, it's quite possible for a U joint that is low on grease to partially seize and bind. You might need to remove the drive shaft and make sure the joints pivot smoothly in both directions.

 

Thanks again for everyone's input. I will take a good look at all possible causes mentioned above...