Vibration at speed between 50 and 60 mph

[AUFordMan]

I am noticing a vibration with a low roar/rumble at speed between 50 and 60 mph while accelerating or decelerating. It's a 2001 Expy with the 4.6 and it has 138,000 miles on it. I also notice a slight woble at 5-10 mph. Could this be either a bad universal joint or has anyone had a problem with the rear end or tranny that had a similar feel/sound?

Thanks for the help!

 

[Thermo]

AU, what you are describing sounds like the cardigan joint problem. But, your truck should not be subject to that. First off, crawl under your truck and look at the U-joints. Make sure that they are good. What I want you to look at specifically is at the front joint of the rear driveshaft (where it comes out of the tranny/transfer case). Do you see what appears to be 2 U-joints back to back with a collar over them. If so, someone swapped out the driveshaft with one from the junk yard that was from a 97-98 Expy. If this is the case, your centering bearing inside the cardigan joint is bad. You need to find a 1350 joint made by ****************er.

But, odds are, you just have a u-joint that is starting to go and you need to replace it here in the near future.

 

[AUFordMan]

Thanks for the information. I think it's going to be the U joints.