There are better net places to seek information about Duramax engines. These engines are good. Make your decision based on your wants/needs and or price.
Go buy a few diesel magazines and you will learn lots. This is a great bus site for some information but not all information. Go to whomever is selling these buses and ask those who have driven or repaired these buses. I have an Int bus with a Ford 7.3 engine. My bus is not the very best. My bus does what I want done. Frank