Okay so the U-joint on my driveshaft went out and it fell off on the freeway. I had a new driveshaft and slip yoke made for the truck and I installed it on my 88 f250. It is a one piece driveshaft. But I just drove it down the road and it is shaking like its unbalanced. Now the driveshaft was balanced though... Anyone have ideas as to what it could be?

 

If it did not vibrate before the u-joint issue then I would say someone did a poor job "balancing" the new driveshaft.

What year/model/engine/transmission truck do you have?

 

I would say u need to have all three pieces driveshaft slip yoke tranny side and diff yoke axle side all balanced at one. As far as I know this is how they do it at the factory and I have made the mistake of not marking my driveshaft when replacing u joints and reversed the alighnment of the yoke it vibrated like crazy. Went back to the garage and turned the yoke then she was smooth as butter. Check both of these things likely to be one or both causing ur problem

 

As an update the transfer case has a broken casting. I jacked it up and put it on stands and let the clutch out and could see it wobbling there. Haven't taken it off yet but i would guess that the output shaft from the tcase is bent or something...