I changed the fluid (Mopar) and took a 4,000 mile round trip to the East coast (Richmond via Danville, VA) towing a small (16 ft.) camp trailer. I liked the shifting before but after the trip it's even better ..... truck has 30k on it now.

 

Yep these trannies shift bad. I love them and wouldnt trade it for the world though. 65k on it with 2 fluid changes and a new clutch in the truck and it is still notchy and shifts worse than a newby with a super 10! That being said, if you drive it like a truck and not a car it will shift decent and put all the power to the ground that the cummins can produce. This thing makes towing the 15k lb trailor a breeze. The G56 shifts a little nicer and is what I will eventually swap into my 12 valve. Only reason being that there is less gear in OD which should help out with the 3.55s when hauling the 5ver. I love the NV4500 the best of the three but hauling heavy stinks with the 3-4 gear gap and constantly worrying about blowing out the OD gears. In all actuallity there isnt a problem with any of the trannys when you think about the fact that thay all will survive well outside of their design parameters and ratings.