Troy and I have been working on a hood report for almost 150 years now, and we're close, but not close enough to publish it! However, yes, for the flat hood there were a few differences between the years. The "alignment" hole Pacecar stated, and a "tab" in the inner structure (see pictures attached).
For the SS hoods, there are a few other/additional differences, but you'll have to wait for the report!!
Ed