They were/are a PITA! I got to work on a couple we raced back in the early 70's! Shel couldn't change the fact that his base AC Ace was designed for a Bristol motor generating a whopping 130 HP! You couldn't own an old Shelby without owning and knowing how to use a TIG as well! Little things like changing the battery in a Cobra was also an involved and VERY costly adventure!