2001 F250 Vibration Or Rough @ 45mph
 

I have a 2001 f250 super duty that seems to vibrate or run rough at about 45mph. I have an automatic transmission, so when I put it into 2nd it soothes out, I don't know if its a transmission or a performance issue. The truck runs fine otherwise. Any ideas for diagnosing this problem? by the way its below zero here so I want to limit my time outside. thanks.

Where does it feel like the vibe is coming from?
Any off-roading or rough road ops?
Have you lost a wheel weight due to those ops?
(quick & dirty answer)

I don't do any off roading snow or ice in the wheels may be an answer however when my truck shifts from 2nd to 3rd it kind of vibrates into third. this has been happening for about a year and a half, I had the transmission checked out at that time and I was told everything was fine. the truck operates just fine other than that. a side note, I do haul a 14' trailer with tools and the such for my work, could I be over working the tranny? I really hope it is something simple like ice or snow in the wheels but transmissions make me nervous.

thanks for your response.