Question: When the View-Master was the official film of Disneyland in the 1970s, an actor whose career spanned how many decades was its spokesman?

Context paragraphs:
List of John Hurt performances: Sir John Hurt, CBE (1940–2017) was an English actor and voice actor whose career spanned six decades.  He had roles in over 130 films with dozens of television roles. .

Gregori Chmara: Gregori Mikhailovich Chmara (Ukrainian: Хмара Григорій Михайлович, Russian: Хмара Григорий Михайлович; 29 July 1878 - 3 February 1970) was a Ukrainian-born stage and film actor whose career spanned six decades.

Henry Fonda: Henry Jaynes Fonda (May 16, 1905 – August 12, 1982) was an American film and stage actor with a career spanning five decades.

Joel McCrea: Joel Albert McCrea (November 5, 1905 – October 20, 1990) was an American actor whose career spanned almost 5 decades and appearances in over 90 films.  These films include Alfred Hitchcock's spy film "Foreign Correspondent" (1940), Preston Sturges' comedy classics "Sullivan's Travels" (1940), and "The Palm Beach Story" (1941), the romance film "Bird of Paradise" (1932), the adventure classic "The Most Dangerous Game" (1933), George Stevens' "The More the Merrier" (1941), and the titular character in the western classic "The Virginian" (1946).  With the exception of the British thriller film "Rough Shoot" (1953), McCrea only appeared in western films from 1946 to his retirement in 1976.  His most notable western is "Ride the High Country" (1962), in which he starred with Randolph Scott.

Michael Sharvell-Martin: Michael Sharvell-Martin (2 February 1944 – 28 October 2010) was a popular British television and stage actor whose career spanned more than three decades.  He was a familiar character actor on British television screens, guest starring in most prime time dramas and comedies throughout the seventies and eighties.

Davis Roberts: Davis Roberts (born Robert A. Davis, March 7, 1917 – July 18, 1993) was an American character actor whose career spanned five decades, from the late 1940s until just before his death in 1993.  He started out making films in the 1940s and 1950s and expanded into television work in the following decades.  Davis was known for his dignified portrayals which were often in contrast to prevailing stereotypical roles.  He played the role of Dr. Caldwell in three episodes in the second and third seasons of the NBC-TV sitcom series "Sanford and Son", and as Dr. Ozaba in the 1968 episode "The Empath" in the original "Star Trek" series.

Andy Clyde: Andrew Allan Clyde (March 25, 1892 – May 18, 1967) was a Scottish-born American film and television actor whose career spanned more than four decades.  In 1921 he broke into silent films as a Mack Sennett comic, debuting in "On a Summer Day".  He was the fifth of six children of theatrical actor, producer and manager John Clyde.  Clyde's brother David and his sister Jean also became screen actors.

GAF Materials Corporation: GAF is a company based in Parsippany, New Jersey, that has roots dating back to the late 19th century.  The GAF acronym stands for General Aniline & Film.  The company has historically been primarily focused on manufacturing of roofing materials for residential and commercial applications.  At one time GAF was also active in manufacturing photographic film as well as cameras and projectors (both still and motion picture), and was the manufacturer of the View-Master, the famous line of 3D transparencies, viewers and projectors.  Briefly in the 1970s, it was the official film of Disneyland and at this time, actor Henry Fonda served as the company's spokesman in several television commercials including one that featured Jodie Foster in her first acting role.

Eli Wallach: Eli Herschel Wallach ( ; December 7, 1915 – June 24, 2014) was an American film, television and stage actor whose career spanned more than six decades, beginning in the late 1940s.  Trained in stage acting, which he enjoyed doing most, he became "one of the greatest 'character actors' ever to appear on stage and screen" states TCM, with over 90 film credits.  On stage, he often co-starred with his wife, Anne Jackson, becoming one of the best-known acting couples in the American theater.  As a stage and screen character actor, Wallach had one of the longest careers in show business, spanning 62 years from his Broadway debut to his last major Hollywood studio movie.

Richard Crane (actor): Richard Ollie Crane (June 6, 1918–March 9, 1969) was a veteran character actor whose career spanned three decades in films and television.  His early career included many uncredited performances in feature films made in the 1940s.

Supporting paragraphs: GAF Materials Corporation Henry Fonda
Answer: five