I am one of the few guys it sounds like who does not particularly like the Mack powered 5 tons. I owned an M52A1. It did have good power, but it was "wierd" power. It pulled well, but really did not feel as though it was pulling strong...if that makes any sense. The interesting thing about my truck...not sure if they are all like this...was that you just floored the truck and ran it up to the governed RPM, which was like 2,100 RPM...you just held your foot to the floor and let her pull. The Mack powered trucks tend to be some of the older trucks and, in my experience, these are the trucks that feel the most worn. I realize this is not always the case, but it was the case with my tractor and several other Macks that I've driven and/or inspected.