I have a new '08 6.4 auto with 4.30's with a custom utility body. I was unable to get any dealer or body co. to put the body I wanted on a F350 cab and chassis so I could get 3.73's. I ended up in an F550 strictly due to the fact the body co. could get me one for $4k less than any other model, F350 or F450. I hate the MPG's. I think it has a lot to due with the shift points for the trans. Truck weighs 12K loaded, 11k empty.

I can climb small local hills in my old 2000 7.3 auto with 3.73's in OD with the truck weighing 12K going to the dump. (actual scaled wt at the dump.) My 08 will not climb the same hill in OD. It wants to shift to 4th almost as soon as I hit the hill. If I am on the throttle at all it wants to go to 3rd! I'm guessing as the truck is set up as an F550, the shift points are set for much heavier loads. The body has a roof so the chances I would ever load this truck past 13k are almost nil.

As I understand it, the motor/trans is the same in the F350, 450, 550's in DRWs. Anyone know if the trans computer can be reprogrammed to that of say a stock F350 or stock F450? The techs at my local Ford dealer are idiots. (took them 3 tries to properly install the batteries on my 2000. One tech recently told me that my F550 6.4 was a tuned DOWN version of the F250 with the 6.4. Suggested I get a faster stock rear when the fastest Ford offers is the 4.3's)

I'd also love to get the engine cranked down to F350 specs or F450 specs if possible. Just trying to find anything I can do to get this pig to run like the truck I originally wanted.