Life & Career cut short

I just watched an old movie called 'the Conversation' that featured this actor. I also remembered him from 'The Deer Hunter' and 'The God Father'. I assumed he went on to have small parts in many movies to come through out the 80s and 90s. Only to find when I looked up his career that he died way back in 1978 at just 42. But what a successful bunch of features to have been involved in during a life that was sadly cut short.