I have a ’63 & I don’t recall the slap/flap phenomenon. However, I drive it 95% of the time with the top down (of course!!). The top has been replaced, but it was on the car when I got it, & will need replacement in the next 1-2 years. I don’t have access to the car right now (in the shop for a few things I just don’t have time to do right now). Michigan weather is iffy right now so I’m not sure I’ll be able to check out how it is put together for awhile. I’ll keep you in mind when I do get it back. Sorry I can’t be of more help right now, but I didn’t want to leave you hanging out there.