I have an '01 F250 4X4, 5.4 auto. This AM at about 45-50 mph, I got a strong vibration. It right at where the OD shifts in. It was fine yesterday. I drove it to the shop with the OD off & it was fine. Any ideas? I'm waiting for the diagnosis. Thanks.

 

Where did the vibration come from, where did it feel stronger, did it quit above 50mph?

It could be 4th gear failing, it could be an out of balanced driveshaft, it could be the alignment/suspension/steering beginning to have issues.