What is the difference between type II and type III ambulances?

There are actually 4 types of ambulances. Type I are built on the chassis of a regular truck, like an F-350 or a Chevy silverado. A type II has no box like what regular ambulances do, so you would see a regular Dodge Sprinter with lights and a logo. Type III is build on the chassis of a van, like a Ford E-350 or a Chevy Savannah. And finally, Medium duty ambulances are huge ambulances.