How very sad. He ruled the teen idol scene in the 70s. Many years ago (probably the 90s) he and his brothers Shaun and Patrick performed the female trio You Could Drive a Person Crazy from the musical Company at a S.T.A.G.E.S. AIDS benefit. Hysterical.
David later did a solo of Madonna's Sooner or Later from Dick Tracy. He was wonderful and such a generous talent to donate his time for such a worthy cause. My favorite moment was the reaction from a middle aged woman wearing all of these "I Love David" buttons seeing him perform two women's numbers. I guess she thought it'd be his greatest hits.