Stop in for a cup of coffee

Hey slant question the drain plug on a 64 is it the big 7/8 head that is supposed to be there? I have a replacement one in the cuda, just looks wrong and shiney. Cant find a good answer.
I would have to go look and see what I have. Only thing is the earliest slant I have is a 1968 and vast majority of slants I have are 72+