Well what a surprise. my 04 f350has a wicked drivetrain vibration! It does not always happen though. Is it possible for the vacuum pump for auto locking hubs to act up and lock hubs in? because when i park the thing i go under and spin the wheel joint and they are unlocked but i still feels like they are locked when driving about 40mph to 70mph. From what i read ford does not acknowledge that this is a problem even though there are like 100 websites that talk about it. PLEASE HELP. If anyone is a pro on this topic any advice would be great!! I have really enjoyed this sight so far thanks to all you have helped in the past!

 

First thing to check is to make sure the hub is all the way in the auto position, if so you might have a hub going out on you, luckily the 04 hubs are alot less expensive than the 05 and up hubs,less than half the cost. If you wind up ordering them make sure to get the right ones, with the ABS sensor, aouto 4x4,and so on. Jack up the truck and then grab the wheel top and bottom and shake it, should be like no play, my sisters truck had one go and there was no doubt what it was. look at the seal on back side of hub to see if it is torn or messed up.

 

Check your carrier bearing in the rear drive shaft.

What do hubs feel like when they are locked and in 2HI? Seriously? I have looked down and realized that I forgot to unlock mine from my last off road session. There have been times when that was over a week. Had I not looked, I wouldn't have known. In short, I can't tell when mine are locked when in 2HI. No vibrations, no hard steers, nothing unusual.

 

If you have a locker in the front like I do you can def feel it while turning and at highway speeds you can feel it, maybe not a vibration but if you put as much windshield time as I do you know there is a difference.
Do you feel the vibration in the steering wheel or in the seat??

 

I can never feel the difference driving down the road if mine is in 4x4 or 2x4. Unless I start making slow speed tight turns. If I romp on it really hard I can tell cause I can feel the drag, but if I'm just cruising I'd never know the difference.

We need more info about this vibration... is it front end or rear end? You can usually tell this by where you feel it, can you feel it in the steering wheel? Or in your butt from the seat?