Yup, you are correct. And then they all started losing them in 1964 when the tires were guaranteed to go the distance without any tire changes. 1964 winner Foyt and several others had their air jacks removed to save weight. And the rear engined cars never had air jacks in that period. There were almost zero tires changed anywhere on the Championship Trail between 1964 and 1970. And it took Penske to bring back air jacks in the late 1970s.