If the assumption is made, right or wrong, that transmission cooler lines are the issue then it might not hurt to get another opinion or two; and do not run the trans fluid low or it will be game over.
ALLDATA shows several TSBs out for the transmission on these cars in relation to cooler line flushing, vent leaks, left side axle seal leaks, etc.
It would be interesting to know if the car has gone through a transmission flush procedure before.