"Very early hoods had folded over lip, no dimples, and no holes for leading edge chrome trim. Intermediate hoods have unfolded lip, small dimples, and no holes for chrome trim. The intermediate hood with the unfolded edges was also used on early 65 cars. Later 65 hoods have the lip folded again, have small dimples, and add the holes for the chrome trim. Later replacement hoods and 66 hoods have larger dimples than the 65 hoods, and still have the folded lip with the holes for the chrome trim."
Found that on the web.