Wow, I often wondered about that gap when the car was on a lift. I’ve notice the same thing with my 68 GTO with the endura bumper. I though maybe my frame was weak. I feel a lot better now that I’m hearing you guys say its normal. By the way during the winter months I store the car with jack stands under the frame. I guess from what I’m hearing I should but a stand under the radiator core support too.
Thanks,
Frank