An episode of Gunsmoke (1955) with this same title aired 18 May 1963 (Season 8, Episode 36). Peter Breck, who played Nick Barkley in this episode, played Jubal Tanner in that one, which was the first of many episodes of "Gunsmoke" written by Paul Savage, who was previously an actor who worked on the "Gunsmoke" radio series. He had also written this "Big Valley" episode the preceding year, his first of three episodes for this series.
Victoria and Jubal Tanner visit the grave site of Jubal's wife. The year of her death is shown as 1854. Both Victoria and Jubal mention that it's been 30 years since she died. That establishes the year of the first season as 1884.
Closing credits: The events, characters and firms depicted in this photoplay are fictitious. Any similarity to actual persons, living or dead, or the actual firms, is purely coincidental.