The numbers are the decider. The 216 and 235 from 1940-1949 look exactly the same until opened see this quote from the Big Truck links:
For '47-'53 AD trucks, though, the medium trucks got the bigger 235 developed during the war. But this engine is NOT THE SAME as the later 235 that came out in '54. Oh no, this engine is not as long (That's why the radiator shroud sheet metal has been cut on trucks with a newer engine installed) and is babbitted. Oh joy!
The good news for an owner of the average medium-duty AD truck, however, is that his original engine probably died an ugly death during the Eisenhower administration and was replaced by a full-pressure oiled 235 (The one in my truck is from a '57 Corvette, believe it or not). Or, once the babbitted 235's came out (they also made better power), bigger truck owners wisely took out their babbitted 235's and used them for a better purpose -- boat anchors.
For the restorer wanting complete originality, my hat is off to them and I wish them bon chance in even finding one of those babbitted 235s, let alone finding someone to rebuild it. Finding mechanicals for that engine will be a quest worthy of an Arthurian Legend in itself. If strict originality is not important, the later 235s can be modified to look and fit like the earlier ones. Several parts vendors sell the kits to make the newer 235's and 261's look like the 216's that go into the light trucks, and that will do nicely for this application, too. How do you tell them apart? The older 235's look a lot like the later ones, except they have 216 visual cues (You might want to ask Barry Weeks for corroboration on this) like the Valve cover with acorn nuts, instead of fastening at the flanges like the later ones do. Also, I don't think the push rod cover surrounds the spark plugs. I've never seen one of these motors, so I can't tell you for sure.
