There's a Chris '74 in Dania Beach, FL that I suspect is Derektor-designed. She's is awful shape and her bottom needs a re-plate quoted at $55k....
My poor relation with Cummins extends back over ten years. The engine is excellent.
Over the years I've owned two airplanes, three boats and three motorhomes. The most recent motorhome is powered by a excellent 500 ISM...
Onan is Cummins...and therein lies the tale of bad and rather uncaring service.
Follow the ground!