He was working out with a therapist, and unfortunately suffered a heart attack. He died shortly after. No link yet, condolences go out to family.
Jeff here's a link http://msn.espn.go.com/classic/obit/s/2002/0911/1430557.html Sorry to hear that he was one of my favorites as a little kid. http://espn.go.com/classic/biography/s/Unitas_Johnny.html
Johnny U was not only great on the field - but great off it as well. He was funny and never felt hurried to scurry off from a fan that wanted to talk football. I talked to him numerous times before Ravens games and he was always pleasent although I knew he had other things he would rather be doing. The Ravens have to put his name and number up in the stadium - he has done far more for the Ravens than Ernest Byner. Not only that - a huge statue should be constructed a la Babe Ruth's statue outside of Camden Yards. Hell, as far as I am concerned the stadium should be Johnny U Stadium. I actually have a grad class with his daughter-in-law and we were just talking on Monday about him.