Specifically 350 (8000 GVW) to 550 (19,700 GVW) range. We run 8 trucks (all diesel) .... 2-350, 1-450 and 5-550. Six are Fords and two Dodge......the two newest Fords are the 6.7 "Scorpion" engine and we have blown both of them with less then 40,000. Ford is refusing to pay for the last one so I'm not too happy at the moment. What are you guys using? Pros and cons? International????