Style 66 is 17" M Parallel, which was recommended by BMW for a winter wheel for the M5. It was also included on M package E39s.
Style 65 was the 18" OEM M5 Wheel..
Which one do you mean? Both are kinda hard to come by in good shape (and OEM) but as Sproule said, check out M5board.com. Although they make it hard to join if you don't have an M5.