[Johnson]

I’ve finally started my cobra project, and I’m looking to clear up some questions. I found the answer to the round/square tail lights, but for now I’m looking to find out when the original chassis started running the square tubing from the front suspension diagonally above the foot wells to the windshield support. I see that the first 289 cars with leaf springs ran a 1 inch round tube, while the later 427 street cars ran a 1 inch square tube. I’m sure some of you know when this change occurred. Thanks for any help.