2002 Chrysler T&C Auto Trans Fault Code P740

I have a Chrysler T&C Van with 106,000 miles on it. The check engine light came on and in checking the fault codes, displayed P740, which has something to do with the torque converter. The vehicle is still running/driving fine, but sometimes will downshift a little hard when coming to a stop. I reset the fault codes and took the vehicle out for a test drive. Everything was fine at city street speeds, however the check engine light came on again at highway speed of about 65MPH. Fault code was again P740. Vehicle is still running fine with the occasional hard downshift when coming to a stop. I contacted the local Chrysler dealer and all they would tell me is that the transmission probably needs to be replaced. Any suggestions or recommendations short of replacing the trans will be helpful. Thanks.