Hello everyone, I have a 1997 F-150 reg. cab 2wd long wheel base 4 speed auto/v-6. less than 57,000k miles on it.
Yesterday out of no where this real bad vibration came over my truck when it reached 72mph. It felt as if a tire was going to come the truck so I got back in the slow lane and got off the road and shut her off, did an inspection of tires and lugnuts and all are fine. I restarted and the problem went away as it never happened any ideas, that was scary as all h_ll.

 

Better go to a alignment shop and have things looked over.

 

Have the tires checked for belt separation.

 

I would be looking at the U-joints. Mine vibrated so bad that I could barely take it anymore and put the thing on jack stands and let it run. I drive shaft looked like it was going to flip completely outta the truck.