He has been doin it for the last 5 years, never bothered anything the only thing he has burnt up was the motor on the boat... A tranny cooler isnt really needed on a Dodge only pulling 2500 lbs, unless your goin up steep grades. They do cut down on wear and tearin the long run though. I have had 6 dodges, towed things from 1000lbs to 25000 lbs, never had a problem. Maybe its just living here in central Mississippi where the ground level varies from 300 to 330 feet. No real hills to worry about