Name the American actor, best known for his role as Captain B.J. Hunnicutt in a television series which included a 2-episode story arc where we see the departure of Captain Trapper and his replacement by this new Captain? 
Welcome to Korea: "Welcome to Korea" was a 2-episode story arc, the 73rd and 74th episodes of the "M*A*S*H" television series, and first two episodes of the fourth season of the series. Welcome to Korea:  First aired on September 12, 1975, the series' first 60 minute episode (double the normal time) was most notable for its off-screen departure of the character of Captain Trapper John McIntyre (played by Wayne Rogers), and his replacement by the freshly drafted Captain B.J. Hunnicutt (played by Mike Farrell).
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