Brad Davis was 26 in Sybil when he played the character 'Richard J. Loomis'.
That was over 46 years ago in 1976.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
In 1991 he died aged just 41, starring in 23 films in his career, 23 of those after Sybil was first released. If he were alive today he would be 73.
In Sybil, I think Brad Davis looks: