Execut1ve

I am asking this for a relative with a 2005 expedition. He is having a pretty severe shudder when the truck tries to shift into overdrive. You could describe it as violent transmission slippage or the torque converter having trouble deciding if it wants to be locked or unlocked. If he drives with the OD button toggled off he has no problems. definitely sounds like a torque converter issue to me, anyone else have any thoughts?