This truck was just assigned to me when it came back from the Mack dealer. They say it just had a partial rebuild that replaced the sleaves and rods and all that stuff. I don't have the details on the truck other than it's a late 1990s tractor with a 6 cylender diesal. The truck runs real smooth and sounds good but it can't go up hills and takes for ever in each gear to get up to speed on the highway. It will do 75+ mph but it takes forever to get there. Our mechanic is a nice guy but hasn't got a clue as to what's wrong. I'm sure they wouldn't have spent the money they did on it if the first 410k miles were put on as slow as the 500 miles I put on it yesterday. Droppng a gear going up about a 3 or 4% grade with 8,000 lbs of freight in the trailer just ain't right. Does anyone have any suggestions on what I can tell our mechanic to check or adjust to help me go up hills with a little less embarrasment. Thank you. Rick