Complex sentence: Dan Blocker made two appearances on the long running Gunsmoke series: the first on August 25,1956 in "Alarm at Pleasant Valley," and the second on October 18,1958 in "Thoroughbreds".
Split into simpler sentences: Dan Blocker made two appearances on the long running Gunsmoke series. The first on August 25,1956 in "Alarm at Pleasant Valley," and the second on October 18,1958 in "Thoroughbreds".