A couple of years ago, I saw something similar sitting at a transmission shop downtown. It was on a Dodge Ram 3500 4X4 chassis. I don't know what transmission it had (the shop does auto tranny and clutch work, so it could have been either). It looked to be mid to late '90s truck, with Cummins. It did seem to have an over cab bed. I don't know the length.
My son had one on a Dodge chassis ('94, IIRC) many years ago. I think it was slightly smaller than the one I saw here, and it was 4X2.
So, they are out there somewhere. Used ones seem to be quite rare. New ones are very pricey, and are probably larger than 24 foot.
Good luck in your search.
EDIT: Originally, they were called a "Chassis-Mount Camper". I see Tiger calls them "Class C motorhomes". Well, yeah, I guess they are a "C".
