I was woundering if someone could help me on a question about my buddys 2000 gmc truck its a 2500 6.0 the transmission will not go into overdrive and in every gear it revs higher than normal even at cruesing speeds. Someone told him it could be a torque converter sensor. I was woundering if this could be the cause or if its something els. If eny one has some ideas that would be sweet thanks.