With 19 laps to go, Joe Leonard led, with Bobby Unser back in second. Carl Williams crashed on the backstretch, triggering a fire which brought out the yellow light. Under the caution, Leonard led, with Bobby Unser and Dan Gurney nose-to-tail. After the cleanup, the green flag was given on lap 191. At that instant, both leader Joe Leonard and his teammate Art Pollard hesitated and instantly slowed with identical snapped fuel pump drive shafts. The turbine engines again failed in sight of the finish, stunning the racing fraternity. Bobby Unser swept by into the lead with Dan Gurney inheriting second place. With a nearly full-lap lead, Unser cruised the final nine laps to win his first 500.