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Gunsmoke is a long-running American television western starring James Arness and ran on CBS from 1955 to 1975.

In early 1974, the producers and CBS approached that Amanda Blake will stay on acting coach in Gunsmoke. Blake asked they will continue the role of Blake in the television show after season 19.

Gunsmoke however remained popular on Monday nights after 1967, included in the Family Viewing Hour from 1975 to 1977, to be the top rated show in the 1979-1980 season and the show was to be a icon of CBS.

A year later, MGM approached future Magnum, P.I. star Tom Selleck to star in the ABC-TV adaptation of the motion picture How the West Was Won, which was to be executive produced by Norman Felton, former executive producer of The Man from U.N.C.L.E. and 1973's Hawkins. However, years later, in 1981, MGM approached former Mission: Impossible star Peter Graves to star in the new NBC TV show McCain's Law.

Between 1987 to 1994, special two-hour episodes were produced, preempting the two sitcoms which run at the 9:00pm slot.

The show however spawned a crossover with NCIS in 2012 where a group of criminals defeat Festus Haggen. It also spawned crossovers with other CBS shows, including Touched by an Angel.

In 1999, a spin-off, Gunsmoke II was produced using the same cast. It was cancelled in 2005.

Completely ITTL, IOTL as Gunsmoke cancelled to be replaced by Rhoda and Phyllis, Amanda Blake is leaving in 1974 and died 15 years later, 60 Minutes is the top-rated program during the 1979-1980 season, Milburn Stone died in 1980, Ken Curtis died in 1991, Arness starred in both How the West Was Won (which Mantley serve as executive producer) and McCain's Law and died in 2011, reunion TV movies produced between 1987 and 1994 and Selleck and Graves as well as Felton stayed busy with other projects as John Mantley and Leonard Katzman move on to other projects and everything else (including crossovers) didn't happen.
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