Yarborough drove for Banjo Matthews at the beginning of 1966. Despite two consecutive second-place finishes, he left the team early in the season and ended the year driving the No. 21 Ford for the Wood Brothers. He won two races in 1967 at the Atlanta 500 and the Firecracker 400 for the Wood Brothers, but dropped to 20th in standings because he only ran 17 races. Yarborough also ran the Indianapolis 500 in 1966 and 1967 driving Vollstedt-Fords. After running the season-opening Middle Georgia 500 for Bud Moore Engineering, finishing 21st, Yarborough ran the rest of the season for the Wood Brothers, winning his first Daytona 500 in a duel with Lee Roy Yarbrough, the Firecracker 400, which made him the second driver in history to sweep both Daytona events, and his first Southern 500 garnering a total of six wins that season. Running a limited schedule, he finished seventeenth in points. The next season, he won his third straight Atlanta 500 along with the first NASCAR race at Michigan International Speedway the Motor State 500 and six pole positions.