Re: what sort of gas millage should I expect from this truck
jim is your truck diesel or gas,
I ran both those versions of your truck, the gas models got 7 mpg and the diesels about 16mpg. this was with a 7ft box and about 11,500 gross weight all the time.
one thing about mileage is take it all with a grain of salt I read alot of diesel pickup truck forums and have owned both ford and dodge. I have NEVER got near the mileage alot of those guys claim and actually call bullshit on it. there are a ton of variables though for one thing out west here we drive faster than many people in the south and east because our freeways are wide open and have higher limits. this does make a big difference. the other thing is people tend to watch their fuel mileage computer and think its gospel. fill the tank, reset the trip mileage, when its empty refill the tank, divide that by the miles on the trip odometer and there you go. that is the only accurate way to know for sure. its surprising how few people seem to be able to grasp that.
I would say that box truck with its higher profile and dual wheels, I would plan on it getting 8-9mpg mixed city highway loaded with a machine and all the accouterments. I have seen some of those interlink box units at the salt lake location, they are really really nice, especially the restoration version.