Thornapple, My International is pretty much like the Col argosy. Condo, Double Bunk, Flat floor, Refreg, Microwave, 5000/2500 inverter with seperate battery supply, M-11 with 350hp, eaton 9sp convertible (can be switched to 13 with gear kit), 28ft box, liftgate, spare tool box, loft in box, quad air ride suspension, dual air ride seats, sony cd with surround sound speakers, plenty of storage.
A 7ft 8" man could stand up and not hit his head. That's the luxury of having a condo. I have had numerous team mates run with over the road for weeks at a time, and we have never had an issue getting in each other's space.
My truck falls short of the argosy in fuel milage. I am averaging 9.4-9.7 mpg for all miles. I set the cruise at 62mph and "baby" the truck getting her up to speed. I'm not racing to get here down the road. I had International set the govenor to 72 mph and the horse was set at 370 and I had it turned down to 350. With 350hp I still have no problems running across the 4th of July pass, Snow Shoe, Black Mountain or anything else.
My average load on the truck has been around 15k. So the average load is a little heavier than most D unit loads.
Hope this helps.