I have a 2016 27' Class C motor home on an F550 chassis with 6.7L diesel. The rear axel ratio is 4.88. My question is. I run 2500 rpm at 70 mph. On long interstate runs am I harming the engine by running 2500 to 3000 rpm all day? It seem to me that I am revving the engine very high. I am considering a change to 4.30 gears. Its an expensive change but I plan to own this unit for many years. Any thoughts are appreciated!