As others have stated, that engine is turbo charged but does not have an aftercooler 9to the best of my knowledge). That Cummins engine (the entire 6B series including the ones that are turbo charged and/or aftercooled) are very dependable engines with parts readily available and most mechanics are very familiar with them. I know an NT 37 owner who has over 10,000 hours on his 6BTA.Can anyone tell me if a 1995 Nordic tug with a Cummins has a turbo ?