Hi I have a 2006 GMC 2500 with the Duramax and automatic transmission with 40.000 miles. My truck runs way to hot when towing and whan I drive with my plow on. I have to slow down or stop to get the guage back down. It will trip the overheat light. It does not lose coolant. I understand that the plow will cause some of the problem however I have had trucks with plows for over 30 years and this different. To me it cant get enough air flow as it does it with the plow on or off and pulling a trailer with out the plow on. Any ideas would be great.