Ah....
But Nicklaus did change his swing at least this many times:
1. Nicklaus "The Kid" swing - Nicklaus shoot 17-under at Augusta in 1965
Really behind it and right leaning torso at the top, more lag, more arched left wrist, more forward lean at impact, famous hang back acid tilted finish.
2. The Lull....Won at Baltusrol, wore visors, putted with white Bulls-Eye - Decides to slim down.
Very still head, slight more upright, almost left lean at the top, less arch, less lean, less axis tilted finish.
3. 1971 Pebble 1-iron through the Golf My Way video era
Sets-up more behind it and stays there, the most upright he ever was, more sweep release, almost no forward lean, also much steeper shoulder turn at the end, and VSP.
4. The Full Swing era
More neutral set-up, flatter but NOT flat, flatter shoulder turn, flatter VSP.
5. Old Jack
Don't laugh, he could still play, and arguably, this started in the 196 Masters, where his swing in the last round, looked different enough than his JACK IS BACK 1980 US Open win.
Lets find some pics and video.....calling Lia!