I posted this here not knowing for sure what is causing the problem. I recently purchased a 1995 Ford F150 XL supercab with a 5.0L engine and auto trans. Problem is that I get a vibration between 30 and 45 MPH. It's not just a steering wheel vibration, the whole truck vibrates. After 45 MPH the problem seems to go away. I checked all three u-joints and the front end seemed tight. The tires are fairly new so I'm assuming that they are balanced properly. I just changed the dist. cap and rotor and the spark plugs were changed 7,000 miles ago. No vibration while in park and reving the engine. Any help is appreciated, I'm at a loss??

 

I would have the tires checked and then rebalanced. That would be the cheapest and easiest place to start. Good luck.

 

I had the front tires balanced and the front end aligned this weekend. Still have the vibration. Shop is calling it a driveline vibration. U-joints seem ok?? Could I have a bad motor and/or trans mount??
Thanks for the help!

 

You may want to pull the drive shaft and have them make sure it is balanced. If you just carry it to a driveline shop they will usually do it for free.