Anyone know about an external cooler to prevent a transmission from overheating and breaking down? I have an Isuzu Rodeo and need a new tranny. The repair guy says it went bad because the radiator didn't have enough outflow to the tranny causing it to overheat. Rather than replace the radiator he recommended to add this external cooler to prevent the problem from occuring again after the tranny is rebuilt. He says it's less $$$ than replacing the radiator. This is not a factory part on the Isuzu, rather something that is added on. Any truth to this or is it just b.s.? Thanks.