There is a bit of a problem with the Duramax engines in the Chevy chassis for a class C . Chevy's service manual for repairing the engine on the full size vans and conversion chassis , says to repair the engine , " lift the body off the frame" something that can't be done after the RV is added.
Here in BC , the government ambulance service had so many service problems with their Duramax equipped ambulances; and the time & $$$; that the poor engine access added to repairs; that after using them for a number years they switched back to the 6l gas engine chassis.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.