Your assumption is correct we came out of a sprinter built by OutsideVan in Portland Or. They IMHO are by far the best at sports oriented Sprinter build outs. It's hard to compare an M1083 to a highly insulted and sound proofed Sprinter. The M1083 compared to an International or a Freigliner is much easier to drive and the visibility is fantastic. I have driven just over 2000 miles this month mostly on back roads going 55mph. The commercial Freigtliners and Internationals are much better at higher highway speeds. But the idea of this project was to enjoy the trip and slow down. Now compared to a Unimog the 1083 leans less and tracks much straighter. In fact I drive it easily with one hand resting on the wheel. Also the AC is ice cold very much unlike a Unimog. The M1083 lacks the sophisticated electronic systems of the Unimog but it's much cheaper and easier to maintain. Hope that helps. Let me know if I can clarify anything.
And I will post pics/video of the cab soon.
Thanks again
Martin.