Complex sentence: When Colasanto died in 1985, Coach was written out as deceased without explanation, and Woody Harrelson joined the cast as Woody Boyd in the fourth season of "Cheers".
Split into simpler sentences: When Colasanto died in 1985, Coach was written out as deceased without explanation. Since then, Colasanto's replacement Woody Harrelson joined the cast as Woody Boyd in the fourth season of "Cheers".