original: The show expanded from a half-hour in length to one hour starting on December 1, 1975.
simplifications: The show went from 30 minutes to one hour on December 1, 1975. The show increased in length to one hour on December 1, 1975. On December 1, 1975, the show increased from a half-hour to one hour. The show expanded to one hour starting on December 1, 1975. It had been previously a half-hour show. The show grew from a half-hour in length to one hour. This began on December 1, 1975. The show expanded from a half-hour in length to one hour on December 1, 1975. The show went from being a half-hour to one hour in 1975. The series changed from a half-hour long to an hour show on December 1, 1975. The show went from a half-hour length to one hour. This change took place on December 1, 1975. The show was extended from half an hour in length to one hour starting on 1 December 1975.