According to some parts catalogs, they are the same part. I'm thinking that the single part they are referring to is a universal replacement that may come with multiple hood prop provisions. etc. There were minor differences between many of the '61 through '74 bonnets supplied on chrome bumper cars. The hinges changed at some point. You could probably make a later bonnet work (because they are dimensionally the same), but expect a few minor differences regarding hood prop locations and the presence (yes or no) of captured nuts for hinges.