No, this isn't true for LX at all actually, and never has been. e.g., 1997/98 chainsets were FC-M739 and FC-M569. In 1999 they were FC-M750 and FC-M570 - the numbers being 5 and 7 swapped around was just a coincidence applying to that period only, although it perhaps makes it easier to remember them. I haven't got a list of 1999 LX Mega 9 numbers, but they were basically in the M57x series. So that means some LX numbers actually went backwards, such as V-brakes from BR-M600 to BR-M570.Splatter Paint":20ctzl3b said:http://mombat.org/Shimano.htm covers XT, swap M7xx for M5xx for the LX numbers, perhaps?