well guys i have a question when im going regular speed and my converter locks at about 40-50 mph the truck starts to shake bad but only when it locks then i go to a higher speed (55-65) and the vibration is very little. they've told me that the clutch on the converter is gone any suggestions if in fact thats it?? btw its a 3000 stall

 

Yes most likely the converter clutch is failing, I would not continue to drive it as a complete failure might result in the loss of the trans also.