Both parts 1 & 2 of "Vengeance" are mentioned in great detail in Quentin Tarantino's 2021 novelization of "Once Upon a Time in Hollywood.
This episode S13.E4, Vengeance aired Oct. 2, 1967 is the first showing for Buck Taylor as Leonard Parker. Later starting with episode S13.E9, The Pillagers aired on Nov.6, 1967, Buck Taylor is cast as Newly O'Brian. He later became one of the main cast members on the series Gunsmoke.