Sportsmobile used to build these vehicles on E350 cargo vans as Class B motorhomes. They cut holes for whatever windows you wanted and for either the pop-top roof or a fixed high roof. Ford discontinued the passenger and cargo versions of the E350 in 2014, only keeping the cutaway because of the large market for Class C motorhomes, small moving trucks, etc.
This new Classic is built on a cutaway and has a fiberglass camper body. That makes it a Class C. If you find and bring in an intact 2014 or earlier E350 cargo van, SMB will still convert it in the same way they did the old units, with the van body itself serving as the structure of the camper (making it strictly Class B). You can buy a new Classic (Class C) or, if you find an old cargo van, you can have them build their original Class B. But they do not chop the body off the back.
There was a time when 98% of Sportsmobiles were built on E350s. The 4x4 conversion vehicles that SMB built are capable of Class 4 trails. 4x4 Sprinter SMBs, even with all Van Compass and Agile Offroad upgrades, are recommended by SMB up to Class 2 trails. Many of the newer people on the board are not familiar with what a true offroad beast SMB used to build and is now beginning to build again. Scroll about 85% of the way down
this page. That beige vehicle you see is not a Classic, it is an original E350 4x4 SMB.
The Youtube video below is a Quigley 4x4 conversion of an E350. Though converted by a different company, it does show you what the old SMB (and now the new Classic) is capable of doing.