If anybody can clarify the whole 640 adv fork spring thing, I also would appreciate it. Mine's a 2001 and I can't seem to find springs anywhere. I'd like to find some .49's. I'm told the 2001's had 48mm WP "Rallye" forks which are apparently different than the "non-rallye" 48mm forks used in subsequent years. Neither Race Tech nor KTM have been able to supply me with springs. Today I will pull a spring and measure it to call Race Tech and see if they can match it up. Other than that, can anyone clarify what years/models are interchangeable and/or tell me who can supply springs for this thing?