CENTURY CITY, Calif. -- David Nelson, who essentially played himself as the eldest* child in the iconic American television series “The Adventures of Ozzie and Harriet,” died today at the age of 74. He was the last surviving member of the Nelson TV family. Doctors have told reporters that Nelson died of complications from colon cancer, the result of a lifetime of drinking warm Coke, but the mysterious presence of police investigators at the scene suggests a more complicated set of circumstances. Further fueling suspicion is news that Tony Dow, who played Wally Cleaver on “Leave it to Beaver,” has been taken into protective custody.