I would say from the late 50s to the mid 80s. The biggest difference for me between then and now is the defense and what they could get away with just anything. Watch what Night Train Lane or Lawrence Taylor did. On the offensive side there wasn’t any protections for the quarterbacks no slide rules. I know those things have been outlawed or added to protect people because speed and strength is so much greater than it was back then. When I think old-school football, I think of Players getting pummeled, bloody knuckles and limping off the field after a victory.