the breather stacks on the 64-5 chrome covers meet the flat vc surface

on the 67 + newer vcs, the vc is raised immediately below where the stack meets the vc

and

on the 67 b-body 440 hp cars the left vc doesnt have the clip for the #7 spark plug wire as the a-body cars do have the #7 wire run on top of the vc therefore have the plug wire clips on them