Here is a 6'1" Mark Richards designed single fly swallow tail twin fin of mine. If you compare this board to the one from '78 in the post 'How good is my wife' you will immediately see how the wide point has dropped down from 1/3 from the nose to near the mid point of the board. Almost all boards in the 70's had a wide point up near the nose with a long drawn out tail designed for long drawn out turns on single fins. Once this new template was perfected in about '83 it has hardly been changed in over 20 years. The other difference you will immediately see (even in my crappy photos) is the size of the fins, particularly the width at the base. The newer board has smaller fins that make the board looser and more manoeuvrable, at the cost of the board sliding and being slower down the line. Personally I like a nice wide fin base for lots of drive and power. Perhaps the addition of the smaller fin led to the twin fin designs period of unpopularity as surfer switched to the new 3 fin designs with more speed.