My F-150 short bed shudders around 40mph. Seemingly when going from 2nd to 3rd gear or when getting onto the highway at around 60mpg.

The shuddering(for lack of a better word) or vibrating hesitation was told to me to be the u-joints needing replacement by my uncle. But my father disagrees but cannot give me anyother solutions besides saying it's the transmission.

Other than that it runs beautifully. Thanks in advance for the replies.

 

had the same issue at 33k. now have 170k btw. dealer rebuilt the trans (so they say) something about a classic problem with a valve in the AODE I think. but I've also heard of this going away with a transmission fluid change.

 

I had same problem at 80K and problem went away with fluid change