According to an American forum of racing enthusiasts, in the 1960s there was a track north of Waco, Texas, called "Mustang Dragstrip". Owner and operator of the strip was one Roy Stone, a Mustang motorcycle dealer (thus the dragstrip's name). It was in activity since 1962 and was closed in 1974, actually owing a fatal accident which happened at the track during a racing event.
Nothing is available about this track and the fatality. I am not able to find information, no newspapers, sites, books, nothing. Even AEB book does not list Mustang Dragstrip in Texas chapter.