traded a 2002 6 litre hd for the duramax about 4 months ago. finnally pulled the fifth wheel to the coast thursday, wowwwww. trailer is 28 ft maybee 9000 lb loaded. last truck really strained over the hills, this truck is a ****ing pulling machine. i absolutaley in love with this allison words cannot describe it. had attitude set level 2 locked out 5th on steep grades egt got to 1200 doig 62 engine temp 210 passing stinking japenneese **it car. oh yeah round trip 300 miles think i got 13 mpg.