These older Detroits were very different... Thanks to the high RPM that 2 stroke engines need to really keep going, these things can sound like 70s sports cars that are going 105 MPH, even though the truck (or a Detroit powered tractor from Oliver or a Detroit powered construction vehicle from Terex or Euclid ) is going a lot slower... It sounds like it's fast, but it's not... Not a nitpick, because I love the character that these Detroit Diesel engines had...