Seen an ad for 2006 Tiffin Motorhomes (Allegro Bay) in this Months Trailer Life built on a Freightliner Chassis. It will have a 300hp 5.9Cummins front engine, Allison 5 speed in 34 to 38 ft length motorhomes. Said it would be slightly higher than the gas fueled Allegro Bay, which starts at $116,500. Maybe this is the start, they have been using the Duramax in Class C.