You could call it a class C, but the RVIA and its classifications and certifications did not yet exist.
The Fleetwood Body long chassis for ambulances, hearses and limousines was also popular for these small motorhomes. This was the "long" chassis shared by Cadillac sedans, Olds 98, top two lines of Buick, and one line of Pontiac.
At funeral homes (which provided most of the ambulance service in that era, with little incentive to get you to the ER on time) the preferred nameplate, at least in SE Michigan, was Cadillac. Specialty ambulance services seemed to like the Pontiac, as it was the least ostentatious marque one could obtain, since Chevrolet did not build on the long wheelbase Fisher Body platform.