Strange wobble coming from my truck
 

My truck is making a strange wobble, it only happens when I am trying to feather the peddle in higher rpms when I am in 3rd gear. It also happens in 4th gear no matter what until about 40-42 mph.at first it felt like an out of balance drive line so I pulled my front one and it's still happening. It sounds kind of like a trough out bearing. I was wondering if you guys have any input. Thank you very much, Rhett.

check your u joints. also i know it sounds funny but your upper and lower ball joints.. i had a truck have some strange wobbling, i thought it was the transmission.. even asked an expert he was scratching his head. turned out it was the upper and lower ball joints on one side.. worth a look anyway.