having just had my transmission rebuilt after 71k miles, I can most assuredly tell you that a cooler is WAY cheaper than a new tranny.
Jeep insists that my towing had nothing to do with the failure that caused the rebuild, but bottom line is.. tranny got
too hot, parts burnt and failed (Or they theorize the parts failed and then the tranny got too hot due to the initial sensor failures)... total cost was close to 3k.
All I can say is thank goodness for an extended warranty and little dashboard
lights that gave me SOME warning. I can't imagine what would have happened if I was towing and it went totally kaput.
btw, I have a cooler.. the one Jeep put in at the factory.. and even that didn't help.