Here is a link to
Inliners International site. Go to their "Casting #s" link.
The 216s all had the the "tall" sideplate cover on the pushrod side of the engine. However, so did the 1941-49 235 truck engines. A friend of mine claims that he can the difference between a 216 and early 235 by looking at the outside, but he won't tell me how. I have read that the early 235s had "235" stamped into the oil pan, but I have never verified that. Here is a link to
a great resource in our Tech Tips section. Hope that this helps. If not, post some pictures of you engine.