The 36 - 206.5 engine is different from the 216 engine. It is slightly longer, the side covers do not match, the timing cover has one less bolt than the 216 and the rear motor mounts are set up differently, among other things. The 216 from 37 to 40 is a version unto itself. In 41, Chevrolet redesigned the 216 and the configuration of the block is different from 37-40 along with some other redesigned items although the physical appearance is much the same.
