I grew up around my grandfather's tractor trailers and 6.2 chevy diesels. He has 3 CTDs now and still has a few of the 6.2s, but doesn't drive them much. I can tell the difference between a 6.2, a 6.5, and Cummins 5.9, and even the old L10 and Formula truck engines just by the smell. I'm also pretty good at telling by the sound what kind of engine it is. Of course, a PowerStroke, GM (any diesel model), and Cummins are pretty easy, but telling a Caterpillar, Detroit, or Cummins truck engine by sound takes some experience. Just walking through a parking lot, I'll smell diesel exhaust and start looking for the truck that matches the smell. Sometimes it's an old Workhorse van with a 6.2 that'll sneak up on you. Those old GM 6.2s didn't have much power, but they would sure blow some black smoke when you floored them!