I just watched the 1973 Australia Grand Final between Cronulla and Manly. There was more "biff" in the first 5 minutes of that match than the entire 20 odd years of Super League. I have no idea what skulls were made of back in the 70's but it definitely was not what they are made from now. Mal Reilly didn't last long (he was hit off the ball and retired with a hip injury after about 20 minutes) but whoever he "tackled" stayed tackled for some considerable time. They don't make players like Cliff Watson anymore. Took the ball up relentlessly no matter how many times he got punched in the face, stamped on or gouged.
Graham Eadie and Bobby Fulton were awesome players though.

One thing you notice, the hooker was there to hook the ball. He didn't play dummy half. There was no fixed dummy half (and I've found a few old NRL games now).