Saw this comment on a Youtube video of about Shelby's Super Snake:

I have an old Cobra story...my late father was a Sales Manager at our local Ford dealer in Orlando, Fl. for several years in the 60's and I heard him tell this story many times over the years...A local dentist walks in and says he'd like to buy a 427 Cobra and requests a test drive. My Dad queries him about his driving background and describes the 289 Cobra and the 427 Cobra and suggests they go on a test drive in the 289...the dentist is firm that he wants to buy the 427 and says he wants to test drive the 427...so my Dad gets the car and they go on a spirited test drive...when they get back to the shop, the dentist is looking pretty shaken and agrees that yeah maybe I should consider and test drive the 289 after all...to which my dad announced...THAT was the 289.